Light projection apparatus, light condensing unit, and light emitting apparatus

ABSTRACT

A light projection apparatus that can produce an elongate light projection pattern is provided. The light projection apparatus includes a fluorescent member which is excited with exciting light and a light projecting member which reflects or transmits the light emanating from the fluorescent member to project it outside. The fluorescent member includes an irradiated region which is irradiated with the exciting light, and the length of the irradiated region in a first direction is greater than its length in a second direction.

This nonprovisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 2011-130907 filed in Japan on Jun. 13, 2011,Patent Application No. 2011-140327 filed in Japan on Jun. 24, 2011, andPatent Application No. 2012-013318 filed in Japan on Jan. 25, 2012, theentire contents of all of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light projection apparatus, a lightcondensing unit, and a light emitting apparatus.

2. Description of Related Art

There are conventionally known light projection apparatus that areprovided with a fluorescent member that is irradiated with laser light(see, for example, JP-A-2003-295319).

JP-A-2003-295319 mentioned above discloses a light source apparatus(light projection apparatus) provided with an ultraviolet LD elementwhich functions as a laser light source, a phosphor (fluorescent orphosphorescent substance; fluorescent member) which converts the laserlight emanating from the ultraviolet LD element into visible light, anda visible-light reflecting mirror which reflects the visible lightemanating from the phosphor. In this light source apparatus, thevisible-light reflecting mirror which reflects the visible lightemanating from the phosphor is provided to illuminate a predeterminedregion ahead of the light source apparatus.

When the light source apparatus disclosed in JP-A-2003-295319 mentionedabove is used, for example, as a headlamp of an automobile, theprojection pattern of the light emitted from the light source apparatusneeds to be controlled. Specifically, the light source apparatus needsto be designed to produce a laterally elongate light projection pattern.Although JP-A-2003-295319 mentioned above does not discuss any lightprojection pattern, the light projection pattern obtained is supposed tobe circular. Inconveniently, this makes it difficult to use the lightsource apparatus disclosed in JP-A-2003-295319 mentioned above as, forexample, a headlamp of an automobile, where a laterally elongate lightprojection pattern is required.

On the other hand, there are conventionally known light condensingmembers that guide laser light while condensing it (see, for example,JP-A-2007-41623). JP-A-2007-41623 discloses (paragraphs [0066]-[0069],and [0079]; FIGS. 8 to 10, and 16) an optical waveguide (lightcondensing member) that includes an entrance face through which laserlight enters and an exit face which has a smaller area than the entranceface. In this optical waveguide, the laser light that has enteredthrough the entrance face is guided to the exit face while beingreflected on the side faces that connect between the entrance face andthe exit face; the light eventually exits through the exit face in acondensed state.

Although JP-A-2007-41623 mentioned above does not discuss it, using anoptical waveguide requires the use of a member that holds the opticalwaveguide. That is, the holding member inevitably makes contact with thesurface of the optical waveguide. For example, in a case where theholding member makes contact with a side face of the optical waveguide,part of the laser light traveling inside the optical waveguide exitsinto, and is absorbed by, the holding member at where the opticalwaveguide and the holding member make contact with each other, becausethere the total reflection condition is not fulfilled. Inconveniently,this lowers the efficiency of use of light (laser light).

As an improvement, JP-A-2007-41623 mentioned above also discloses astructure in which an Ag layer for reflecting laser light is provided onthe side faces of the optical waveguide. Since the reflectance of Ag isabout 95%, however, the laser light is absorbed by the Ag layer eachtime it is reflected on it. This lowers the efficiency of use of light(laser light).

SUMMARY OF THE INVENTION

The present invention has been devised to overcome the inconveniencesmentioned above, and an object of the invention is to provide a lightprojection apparatus, a light projection unit, and a light condensingmember that can produce an elongate light projection pattern.

Another object of the invention is to provide a light condensing unitand a light emitting apparatus that can suppress lowering in theefficiency of use of light.

To achieve the above objects, according to one aspect of the invention,a light projection apparatus is provided with: a fluorescent memberwhich is excited with exciting light; and a light projecting memberwhich reflects or transmits light emanating from the fluorescent memberto project the light outside. Here, the fluorescent member includes anirradiated region which is irradiated with the exciting light, and thelength of the irradiated region in a first direction is greater than thelength of the irradiated region in a second direction perpendicular tothe first direction.

In this light projection apparatus, as mentioned above, the length ofthe irradiated region in the first direction is greater than its lengthin the second direction. Thus, the fluorescent member is excited in anarea elongate in the first direction. As a result, projecting the lightemanating from the fluorescent member outside through the lightprojecting member produces a light projection pattern having an elongateshape that is elongate in the first direction.

In the present specification, an elongate shape denotes a shape of whichthe length in a predetermined direction is greater than its length inthe direction perpendicular to the predetermined direction; such shapesinclude, for example, elliptical, rectangular, and oval shapes, and maybe asymmetric in the up-down or left-right direction.

In the above-described light projection apparatus, preferably, there isfurther provided a light condensing member which includes a lightentrance face through which the exciting light enters and a light exitface that has a smaller area than the light entrance face and throughwhich the exciting light exits. Here, the length of the light exit facein the first direction is greater than the length of the light exit facein the second direction. Making the length of the light exit face in thefirst direction greater than its length in the second direction in thisway makes it easy to make the length of the irradiated region of thefluorescent member in the first direction greater than its length in thesecond direction. Moreover, forming the light exit face of the lightcondensing member with a smaller area than the light entrance facepermits the exciting light that has entered through the light entranceface to exit through the light exit face in a condensed state.

In the above-described light projection apparatus, preferably, theirradiated region has a rectangular, elliptical, or elongate hexagonalshape.

In the above-described light projection apparatus, preferably, theirradiated region has a shape asymmetric in the first direction. Withthis design, it is easy to give the light projection pattern a shapeasymmetric in the first direction.

In the above-described light projection apparatus, preferably, the focusof the light projecting member is located at an edge of the irradiatedregion. With this design, it is possible to change illuminance sharplyat a part of the light projection pattern which corresponds to the edgeof the irradiated region where the focus of the light projecting memberis located.

In the above-described light projection apparatus where the focus of thelight projecting member is located at an edge of the irradiated region,preferably, the light projection apparatus is used as a headlamp of anautomobile, and the focus of the light projecting member is located atan edge of the irradiated region from where a cut-off line of the lightprojection pattern is projected. This design is particularly effective,making it possible to change illuminance sharply at the cut-off line

In the present specification and the appended claims, a cut-off linedenotes a line dividing between the bright and dim areas in the lightprojection pattern of a low beam (a passing-by headlamp). At a cut-offline, a sharp change in illuminance is required.

In this case, preferably, the focus of the light projecting member islocated at a position on the irradiated region from where an elbow pointof the light projection pattern is projected. This design is moreeffective, making it possible to change illuminance sharply near theelbow point. Moreover, it is possible to obtain the highest illuminancenear the elbow point. That is, it is possible to illuminate a regionright ahead of an automobile with the highest illumination.

In the present specification and the appended claims, an elbow pointdenotes the intersection between the left-half and right-half cut-offlines in the light projection pattern of a low beam (a passing-byheadlamp).

In the above-described light projection apparatus, preferably, thelength of the irradiated region in the first direction is three times ormore as great as its length in the second direction. With this design,it is possible to make the ratio of the length of the light projectionpattern in the first direction to its length in the second directionequal to three or more. For example, in a headlamp for an automobile,the aspect ratio of a proper light projection pattern is about 1:3 to1:4, and thus using the light projection apparatus as a headlamp in anautomobile makes it possible to illuminate ahead properly.

In the above-described light projection apparatus provided with thelight condensing member, preferably, the light exit face is formed in arectangular, elliptical, or elongate hexagonal shape. With this design,it is easy to define the shape of the irradiated region of thefluorescent member.

In the above-described light projection apparatus provided with thelight condensing member, preferably, the light exit face has a shapeasymmetric in the first direction. With this design, it is easy to givethe light projection pattern a shape asymmetric in the first direction.

In the above-described light projection apparatus where the light exitface has a shape asymmetric in a first direction, preferably, the lightprojection apparatus is used as a headlamp of an automobile, and thelight exit face is formed in a shape that corresponds to a lightprojection pattern of a passing-by headlamp. With his design, it is easyto realize a light projection pattern needed in a passing-by headlamp.

In the above-described light projection apparatus provided with thelight condensing member, preferably, the length of the light exit facein the first direction is three times or more as great as its length inthe second direction. With this design, it is possible to make thelength of the irradiated region in the first direction three times ormore as great as its length in the second direction; thus, it ispossible to make the ratio of the length of the light projection patternin the first direction to its length in the second direction equal tothree or more. For example, in a headlamp for an automobile, the aspectratio of a proper light projection pattern is about 1:3 to 1:4, and thususing the light projection apparatus as a headlamp in an automobilemakes it possible to illuminate ahead properly.

In the above-described light projection apparatus, preferably, the lightprojecting member includes a reflecting member which reflects the lightemanating from the fluorescent member to project the light outside. Withthis design, it is easy to project the light emanating from thefluorescent member in a predetermined direction.

In the above-described light projection apparatus, preferably, the lightprojecting member includes a lens which transmits the light emanatingfrom the fluorescent member to project the light outside. With thisdesign, it is easy to project the light emanating from the fluorescentmember in a predetermined direction.

In the above-described light projection apparatus where the lightprojecting member includes a lens, preferably, the light projectingmember includes the lens and a reflecting member having a reflectingface that reflects the light emanating from the fluorescent member, thereflecting face is formed as an ellipsoid, the first focus of thereflecting face is located in the irradiated region, and the secondfocus of the reflecting face coincides with the focus of the lens. Withthis design, the light emanating from the irradiated region is reflectedon the reflecting face, passes through the second focus of thereflecting face, and is projected by the lens. Here, since the secondfocus of the reflecting face coincides with the focus of the lens, it iseasier for the light projection pattern formed by the lens to reflectthe shape of the irradiated region. Projecting light with a lens, ascompared with projecting light with a reflecting member withoutproviding a lens, makes it easier for the light projection pattern toreflect the shape of the irradiated region. Moreover, providing areflective member, as compared with projecting light with a lens withoutproviding a reflecting member, makes it possible to use more of thelight emanating from the fluorescent member as illumination light. Thishelps improve the efficiency of use of light.

In the present specification and the appended claims, a first focusdenotes, of the foci of the reflecting face, the one closer to itsvertex, and a second focus denotes the one farther away from it.

In the above-described light projection apparatus where the lightprojecting member includes a reflecting member, preferably, thereflecting member includes a reflecting face which reflects the lightemanating from the fluorescent member, the reflecting face is formed asa paraboloid, and the focus of the reflecting face is located in theirradiated region. With this design, it is easier for the lightprojection pattern formed by the reflecting member to reflect the shapeof the irradiated region.

In the above-described light projection apparatus, preferably, the lightprojecting member includes a lens which transmits the light emanatingfrom the fluorescent member to project the light outside, and the focusof the lens is located in the irradiated region. With this design, it iseasier for the light projection pattern formed by the lens to reflectthe shape of the irradiated region. Projecting light with a lens, ascompared with projecting light with a reflecting member withoutproviding a lens, makes it easier for the light projection pattern toreflect the shape of the irradiated region.

In the above-described light projection apparatus provided with thelight condensing member, preferably, the light exit face is a coarsesurface or a moth-eye surface. With this design, it is possible tosuppress reflection on the inner side of the light exit face, and thusto take out light efficiently.

In the above-described light projection apparatus, preferably, theexciting light includes laser light.

According to another aspect of the invention, a light projection unit isprovided with: a light condensing member which includes a light entranceface through which exciting light enters and a light exit face that hasa smaller area than the light entrance face and through which theexciting light exits; a fluorescent member which is irradiated with theexciting light emanating from the light condensing member; and areflecting member which includes a reflecting face that reflects thelight emanating from the fluorescent member in a predetermineddirection. Here, the fluorescent member includes an irradiated regionwhich is irradiated with the exciting light, the focus of the reflectingface is located in the irradiated region, and the length from the focusof the reflecting face to the end of the irradiated region in a thirddirection is smaller than one-half of the length of the irradiatedregion in a fourth direction perpendicular to the third direction.

In this light projection unit, as described above, the length from thefocus of the reflecting face to the end of the irradiated region in thethird direction is smaller than one-half of the length of the irradiatedregion in the fourth direction perpendicular to the third direction.Thus, the distance from the end of the irradiated region in the thirddirection to the focus of the reflecting face is shorter than thedistance from the end of the irradiated region in the fourth directionto the focus of the reflecting face. Thus, it is possible to make thelength of the light projection pattern in the third direction smallerthan its length in the fourth direction. That is, it is possible toobtain an elongate light projection pattern that is elongate in thefourth direction.

Moreover, forming the light exit face of the light condensing memberwith a smaller area than the light entrance face permits the excitinglight that has entered through the light entrance face to exit throughthe light exit face in a condensed state. Moreover, providing thereflecting member makes it easy to project the light emanating from thefluorescent member in a predetermined direction.

According to yet another aspect of the invention, a light condensingmember for condensing exciting light and shining the exciting light ontoa fluorescent member is provided with: a light entrance face throughwhich the exciting light enters; and a light exit face that has asmaller area than the light entrance face and through which the excitinglight exits. Here, the length of the light exit face in a firstdirection is greater than the length of the light exit face in a seconddirection.

In this light condensing member, as described above, by making thelength of the light exit face in the first direction greater than itslength in the second direction, it is possible to make the length of theirradiated region of the fluorescent member in the first directiongreater than its length in the second direction. Thus, the fluorescentmember is excited in an area elongate in the first direction. This makesit possible to obtain an elongate light projection pattern that iselongate in the first direction. Moreover, forming the light exit faceof the light condensing member with a smaller area than the lightentrance face permits the exciting light that has entered through thelight exit face to exit through the light exit face in a condensedstate.

According to a still another aspect of the invention, a light projectionunit is provided with: a light condensing member designed as describedabove; and a fluorescent member which is irradiated with the excitinglight emanating from the light condensing member.

According to a further aspect of the invention, a light condensing unitis provided with: a light condensing member which includes a lightentrance face through which laser light enters and a light exit facethat has a smaller area than the light entrance face and through whichthe laser light exits; and a holding member which holds the lightcondensing member. Here, the light condensing member further includes aside face which connects between the light entrance face and the lightexit face, the side face has a function of reflecting the laser lightthat has entered through the light entrance face to guide the laserlight to the light exit face, the light condensing member is formed of asubstance having a higher refractive index than the environment aroundthe light condensing member, and the holding member holds the lightentrance face, or holds the side face at a point or along a line.

In this light condensing unit, as described above, a light condensingmember is provided which includes a light entrance face through whichlaser light enters and a light exit face that has a smaller area thanthe light entrance face and through which the laser light exits, and thelight condensing member includes a side face which reflects the laserlight that has entered the light condensing member through the lightentrance face to guide the laser light to the light exit face. Thus, thelaser light that has entered through the light entrance face is guidedto the light exit face while being reflected on the side face, and exitsthrough the light exit face in a condensed state. Moreover, the laserlight that has entered through the light entrance face travels insidethe light condensing member while being reflected on the side face, andexits through the light exit face with an even light intensitydistribution.

Moreover, as described above, the holding member which holds the lightcondensing member holds the light entrance face, or holds the side faceat a point or along a line. In a case where the holding member holds thelight entrance face, when laser light is reflected on the side face, itis not absorbed by the holding member. In a case where the holdingmember holds the side face at a point or along a line, it is possible tosufficiently reduce the contact area between the light condensing memberand the holding member. This makes it possible to prevent laser lightfrom exiting into and being absorbed by the holding member at where thelight condensing member and the holding member make contact with eachother. That is, it is possible to reduce the amount of laser lightabsorbed by the holding member.

In the above-described light condensing unit, preferably, the holdingmember has a function of transmitting the laser light and in additionholds the light entrance face. With this design, it is possible tosuppress absorption of laser light by the holding member, and this makesit possible to dispose the holding member so as to the cover the lightentrance face. This makes it easy to hold the light entrance face withthe holding member.

In the above-described light condensing unit where the holding memberholds the light entrance face, preferably, the holding member holds thelight entrance face via an adhesive layer. With this design, it is easyto hold the light entrance face with the holding member.

In the above-described light condensing unit, preferably, there isfurther provided a housing member which houses a laser generator whichemits the laser light, and the housing member includes the holdingmember.

In the above-described light condensing unit, preferably, the holdingmember holds at least one of a light entrance face side part and a lightexit face side part of the side face. The light condensing member isbulkier and heavier in its light entrance face side part than in itslight exit face side part; therefore, letting the holding member holdthe light entrance face side part of the side face allows more stableholding of the light condensing member. Moreover, less laser lightreaches the side face in the light entrance face side part of the lightcondensing member than in its light exit face side part; thus, holdingthe light entrance face side part of the side face helps further reducethe amount of laser light absorbed by the holding member. The holdingmember may hold at least the light exit face side part of the side face.

In the above-described light condensing unit where the holding memberholds at least one of a light entrance face side part and a light exitface side part of the side face, preferably, the holding member includesa line contact portion which makes line contact with the lightcondensing member, and the line contact portion is formed of metal. Withthis design, it is possible to further reduce the amount of laser lightabsorbed by the holding member.

In the above-described light condensing unit where the holding memberholds at least one of a light entrance face side part and a light exitface side part of the side face, preferably, the holding member includesa point contact portion which makes point contact with the lightcondensing member, and the point contact portion has lower hardness thanthe light condensing member. With this design, it is possible tosuppress damage inflicted by the point contact portion of the holdingmember on the light condensing member.

In the above-described light condensing unit where the holding memberholds at least one of a light entrance face side part and a light exitface side part of the side face, preferably, the holding member includesa point contact portion which makes point contact with the lightcondensing member, and the part of the point contact portion at which itmakes contact with the light condensing member is formed as a curvedsurface. This design is particularly effective, making it possible tomake the contact area between the holding member and the lightcondensing member extremely small.

In the above-described light condensing unit where the holding memberholds at least one of a light entrance face side part and a light exitface side part of the side face, preferably, the cross section of thelight condensing member on a plane perpendicular to the light guidedirection has a polygonal shape with a plurality of vertices, and theholding member makes contact with at least two of the vertices. Withthis design, the holding member can be brought into point contact orline contact with the light condensing member, and this makes itpossible to further reduce the amount of laser light absorbed by theholding member. The laser light guided inside the light condensingmember is less likely to reach the vertices of the cross section of thelight condensing member; that is, the density of laser light at thevertices of the light condensing member is lower than the density oflaser light elsewhere. This makes it possible to further reduce theamount of laser light absorbed by the holding member.

In the above-described light condensing unit where the holding memberholds at least one of a light entrance face side part and a light exitface side part of the side face, preferably, the cross section of thelight condensing member on a plane perpendicular to the light guidedirection has a polygonal shape with a plurality of sides, and theholding member makes contact with at least one of the shortest of thesides. With this design, it is easy to hold the light condensing memberstably.

In the above-described light condensing unit where the holding memberholds at least one of a light entrance face side part and a light exitface side part of the side face, preferably, the holding member isformed so as to cover the side face of the light condensing member. Withthis design, it is possible to prevent the laser light exiting throughthe side face of the light condensing member from leaking out of thelight condensing unit; thus, it is possible to suppress adverse effectsof laser light on the human eye etc.

In the above-described light condensing unit, preferably, there isfurther provided a fluorescent member which is irradiated with the laserlight emanating from the light condensing member and which converts atleast part of the laser light into fluorescence to emit thefluorescence.

In the above-described light condensing unit provided with a fluorescentmember, preferably, there is further provided a reflecting member whichreflects the fluorescence emanating from the fluorescent member in apredetermined direction.

In the above-described light condensing unit, preferably, laser lightemitted from a plurality of laser generators enters the light condensingmember through the light entrance face. By use of this light condensingmember, it is easy to condense the laser light emitted from a pluralityof laser generators. Using this light condensing member is thereforeparticularly effective in a case where a plurality of laser generatorsare used as a laser light source.

In the above-described light condensing unit, preferably, the light exitface is a coarse surface or a moth-eye surface. With this design, it ispossible to suppress reflection on the inner side of the light exitface, and thus to take out light efficiently.

According to a still further aspect of the invention, a light emittingapparatus is provided with: a light condensing unit designed asdescribed above; and a laser generator which emits laser light towardthe light condensing member of the light condensing unit.

According to an even further aspect of the invention, a light condensingunit is provided with: a light condensing member which includes a lightentrance face through which laser light enters and a light exit facethat has a smaller area than the light entrance face and through whichthe laser light exits; and a holding member which holds the lightcondensing member. Here, the light condensing member includes a passageregion through which the laser light passes and a no-passage regionthrough which the laser light does not pass, and the holding memberholds the no-passage region.

In this light condensing unit, as described above, a light condensingmember which includes a light entrance face through which laser lightenters and a light exit face that has a smaller area than the lightentrance face and through which the laser light exits is provided. Thus,the laser light that has entered through the light entrance face exitsthrough the light exit face in a condensed state.

Moreover, as described above, the light condensing member includes apassage region through which the laser light passes and a no-passageregion through which the laser light does not pass, and the holdingmember holds the no-passage region. Thus, the laser light is notabsorbed by the holding member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing the structure of a light projectionapparatus provided with a light projection unit in a first embodiment ofthe invention;

FIG. 2 is a perspective view showing the structure of the lightprojection apparatus in the first embodiment of the invention;

FIG. 3 is a perspective view showing the structure of a laser generatingdevice in the first embodiment of the invention;

FIG. 4 is a perspective view showing the structure of semiconductorlaser elements and a heat spreader in the first embodiment of theinvention;

FIG. 5 is a perspective view showing the structure of a semiconductorlaser element in the first embodiment of the invention;

FIG. 6 is a perspective view showing a laser generating device fittedwith a light condensing member in the first embodiment of the invention;

FIG. 7 is a diagram illustrating laser light emitted from asemiconductor laser element in the first embodiment of the invention;

FIG. 8 is a perspective view illustrating the structure of a lightcondensing member in the first embodiment of the invention;

FIG. 9 is a top view showing the structure of a light condensing memberin the first embodiment of the invention;

FIG. 10 is a side view showing the structure of a light condensingmember in the first embodiment of the invention;

FIG. 11 is a side view illustrating the travel of laser light that hasentered a light condensing member in the first embodiment of theinvention;

FIG. 12 is a top view illustrating the travel of laser light that hasentered a light condensing member in the first embodiment of theinvention;

FIG. 13 is a top view showing a modified example of arrangementdirections of semiconductor laser elements in the first embodiment ofthe invention;

FIG. 14 is a top view showing a modified example of a light condensingmember in the first embodiment of the invention;

FIG. 15 is a perspective view showing a modified example of a lightcondensing member in the first embodiment of the invention;

FIG. 16 is a front view showing the light exit face of the lightcondensing member shown in FIG. 15;

FIG. 17 is a perspective view showing a modified example of a lightcondensing member in the first embodiment of the invention;

FIG. 18 is a diagram illustrating a light intensity distribution oflaser light on the light exit face of a light condensing member in thefirst embodiment of the invention;

FIG. 19 is a diagram showing the structure of and around a fluorescentmember in the first embodiment of the invention;

FIG. 20 is a perspective view showing a fluorescent member of which onlya central part is irradiated with laser light;

FIG. 21 is a diagram illustrating an irradiated region on a fluorescentmember in the first embodiment of the invention;

FIG. 22 is a sectional view illustrating the structure of a reflectingmember in the first embodiment of the invention;

FIG. 23 is a front view illustrating the structure of a reflectingmember in the first embodiment of the invention;

FIG. 24 is a diagram illustrating a light projection pattern produced bythe light projection apparatus in the first embodiment of the invention;

FIG. 25 is a sectional view showing the structure of a light projectionapparatus in a second embodiment of the invention;

FIG. 26 is a perspective view showing the structure of a lightcondensing member in a third embodiment of the invention;

FIG. 27 is a diagram illustrating an irradiated region on a fluorescentmember in the third embodiment of the invention;

FIG. 28 is a diagram showing a light intensity distribution of laserlight on a fluorescent member in the third embodiment of the invention;

FIG. 29 is a diagram showing a light intensity distribution offluorescence at 25 m ahead of a light projection apparatus in the thirdembodiment of the invention;

FIG. 30 is a sectional view showing the structure of a light projectionapparatus in a fourth embodiment of the invention;

FIG. 31 is a perspective view showing the structure of a lightcondensing member in the fourth embodiment of the invention;

FIG. 32 is a diagram illustrating an irradiated region on a fluorescentmember in the fourth embodiment of the invention;

FIG. 33 is a diagram illustrating a light projection pattern produced bya light projection apparatus in the fourth embodiment of the invention;

FIG. 34 is a sectional view showing the structure of a light projectionapparatus in a fifth embodiment of the invention;

FIG. 35 is a perspective view showing the structure of a lightcondensing member in the fifth embodiment of the invention;

FIG. 36 is a diagram illustrating an irradiated region on a fluorescentmember in the fifth embodiment of the invention;

FIG. 37 is a diagram illustrating a light projection pattern at 25 mahead of a light projection apparatus in the fifth embodiment of theinvention;

FIG. 38 is a diagram illustrating a light projection pattern required ina low beam of an automobile;

FIG. 39 is a sectional view showing the structure of a light projectionapparatus in a sixth embodiment of the invention;

FIG. 40 is a perspective view showing the structure of a lightcondensing member in the sixth embodiment of the invention;

FIG. 41 is a sectional view showing the structure of a light projectionapparatus in a seventh embodiment of the invention;

FIG. 42 is a perspective view showing the structure of a lightcondensing member in a first modified example of the invention;

FIG. 43 is a diagram showing a part, around a lens, of a lightprojection apparatus in a second modified example of the invention;

FIG. 44 is a sectional view showing the structure of a light projectionapparatus in a third modified example of the invention;

FIG. 45 is a sectional view showing the structure of a light projectionapparatus in a fourth modified example of the invention;

FIG. 46 is a sectional view showing the structure of a light projectionapparatus in a fifth modified example of the invention;

FIG. 47 is a sectional view showing the structure of a light emittingapparatus provided with a light condensing unit in an eighth embodimentof the invention;

FIG. 48 is a perspective view showing the structure of a light emittingapparatus in the eighth embodiment of the invention;

FIG. 49 is a perspective view showing the structure of a lasergenerating device in the eighth embodiment of the invention;

FIG. 50 is a perspective view showing the structure of a lightcondensing member and a glass plate in the eighth embodiment of theinvention;

FIG. 51 is a perspective view showing a laser generating device fittedwith a light condensing member in the eighth embodiment of theinvention;

FIG. 52 is a top view showing the structure of a light condensing memberand a glass plate in the eighth embodiment of the invention;

FIG. 53 is a perspective view illustrating the structure of a lightcondensing member in the eighth embodiment of the invention;

FIG. 54 is a top view showing the structure of a light condensing memberin the eighth embodiment of the invention;

FIG. 55 is a side view showing the structure of a light condensingmember in the eighth embodiment of the invention;

FIG. 56 is a side view illustrating the travel of laser light that hasentered a light condensing member in the eighth embodiment of theinvention;

FIG. 57 is a top view illustrating the travel of laser light that hasentered a light condensing member in the eighth embodiment of theinvention;

FIG. 58 is a top view showing a modified example of arrangementdirections of semiconductor laser elements in the eighth embodiment ofthe invention;

FIG. 59 is a top view showing a modified example of a light condensingmember in the eighth embodiment of the invention;

FIG. 60 is a perspective view showing a modified example of a lightcondensing member in the eighth embodiment of the invention;

FIG. 61 is a front view showing the light exit face of the lightcondensing member shown in FIG. 60;

FIG. 62 is a perspective view showing a modified example of a lightcondensing member in the eighth embodiment of the invention;

FIG. 63 is a diagram illustrating a light intensity distribution oflaser light on the light exit face of a light condensing member in theeighth embodiment of the invention;

FIG. 64 is a diagram showing the structure of and around a fluorescentmember in the eighth embodiment of the invention;

FIG. 65 is a perspective view showing a fluorescent member of which onlya central part is irradiated with laser light;

FIG. 66 is a sectional view illustrating the structure of a reflectingmember in the eighth embodiment of the invention;

FIG. 67 is a front view illustrating the structure of a reflectingmember in the eighth embodiment of the invention;

FIG. 68 is a perspective view showing the structure of a lightcondensing member and metal belts in a ninth embodiment of theinvention;

FIG. 69 is a top view showing the structure of a light condensing memberin the ninth embodiment of the invention;

FIG. 70 is a side view showing the structure of a light condensingmember in the ninth embodiment of the invention;

FIG. 71 is a top view showing the structure of a light condensing memberand semiconductor laser elements in the ninth embodiment of theinvention;

FIG. 72 is a diagram illustrating experiments conducted to verify theeffect of a holding member in the ninth embodiment of the invention;

FIG. 73 is a perspective view showing the structure of a lightcondensing member and a holding member in a tenth embodiment of theinvention;

FIG. 74 is a sectional view showing the structure of a light condensingmember and a holding member in a tenth embodiment of the invention;

FIG. 75 is a top view showing the structure of a light condensing memberand semiconductor laser elements in the tenth embodiment of theinvention;

FIG. 76 is a perspective view showing a modified example of a holdingmember in the tenth embodiment of the invention;

FIG. 77 is a sectional view showing the structure of a light condensingmember and a holding member in the tenth embodiment of the invention;

FIG. 78 is a perspective view showing the structure of a lightcondensing member and a holding member in an eleventh embodiment of theinvention;

FIG. 79 is a sectional view showing the structure of a light condensingmember and a holding member in the eleventh embodiment of the invention;

FIG. 80 is a sectional view showing the structure of a light condensingmember and a holding member in a twelfth embodiment of the invention;

FIG. 81 is a perspective view illustrating a holding member in a sixthmodified example of the invention;

FIG. 82 is a perspective view showing the structure of a light emittingapparatus in a seventh modified example of the invention;

FIG. 83 is a perspective view showing the structure of a miniaturepackage in a light emitting apparatus in the seventh modified example ofthe invention;

FIG. 84 is a top view showing the structure of a light condensing memberin an eighth modified example of the invention;

FIG. 85 is a side view showing the structure of a light condensingmember in the eighth modified example of the invention;

FIG. 86 is a diagram showing relevant dimensions of a light condensingmember in the eighth modified example of the invention;

FIG. 87 is a sectional view showing the structure of a light condensingunit in a ninth modified example of the invention; and

FIG. 88 is a sectional view showing the structure of a light emittingapparatus in a tenth modified example of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings. For the sake of easyunderstanding, hatching may occasionally be omitted even in sectionalviews, and may occasionally be applied elsewhere than in sectionalviews.

First Embodiment

First, with reference to FIGS. 1 to 23, the structure of a lightprojection apparatus 1 according to a first embodiment of the inventionwill be described. For the sake of simple illustration, not allsemiconductor laser elements 11 are always illustrated.

The light projection apparatus 1 according to the first embodiment ofthe invention is used as a headlamp for illuminating ahead of, forexample, an automobile or the like. As shown in FIGS. 1 and 2, the lightprojection apparatus 1 is provided with a laser generating device 10which functions as a laser light source (exciting light source) and alight projecting unit 20 which, by using the laser light emanating fromthe laser generating device 10, projects light in a predetermineddirection (direction A). In FIG. 2, for the sake of easy understanding,a fitting portion 24 b, a filter member 25, and a support plate 26,which will be described later, of the light projecting unit 20 areomitted.

As shown in FIG. 3, the laser generating device 10 includes a pluralityof semiconductor laser elements 11 (laser generators), a heat spreader12 on which the semiconductor laser elements 11 are mounted, and ahousing member 13 which houses them all.

The heat spreader 12 is formed, for example, as a flat plate of aluminumnitride, and is soldered to the bottom face of the housing member 13. Asshown in FIG. 4, the heat spreader 12 has, for example, a width (W12) ofabout 15 mm, a thickness (T12) of about 1 mm, and a depth (L12) of about2 mm. On the mounting face of the heat spreader 12, electrode patterns12 a and 12 b, each elongate, are formed. On the electrode pattern 12 a,a plurality of semiconductor laser elements 11 arrayed in a row aremounted. In this embodiment, for example, 13 semiconductor laserelements 11 are mounted across a width (W12 a) of about 10 mm. It ispreferable that the width (W12 a) here be smaller than the width (W21 a)of the light entrance face 21 a of a light condensing member 21, whichwill be described later, of the light projecting unit 20.

The semiconductor laser elements 11 are, for example, broad area lasers,and emit laser light that functions as exciting light. The semiconductorlaser elements 11 are designed to emit blue-violet laser light with acenter wavelength of, for example, about 405 nm. Moreover, as shown inFIG. 5, each semiconductor laser element 11 has, for example, a width(W11) of about 200 μm, a thickness (T11) of about 100 μm, and a length(L11) of about 1000 μm.

The semiconductor laser element 11 includes a substrate 11 a of n-typeGaN with a thickness of about 100 μm and, formed on top of the substrate11 a in the order named, a buffer layer 11 b of n-type GaN with athickness of about 0.5 μm, a lower clad layer 11 c of n-typeAl_(0.05)Ga_(0.95)N with a thickness of about 2 μm, an active layer 11 dof InGaN composed of multiple quantum wells, and an upper clad layer 11e of p-type Al_(0.05)Ga_(0.95)N with a thickness of about 0.5 μm (at itsthickest part).

At a predetermined position on the upper clad layer 11 e, a ridge isprovided which extends in the Z direction (the length direction of thesemiconductor laser element 11). On the ridge, there are formed acontact layer 11 f of p-type GaN with a thickness of about 0.1 μm and anelectrode 11 g of Pd. The top face of the upper clad layer 11 e and theside faces of the contact layer 11 f and of the electrode 11 g arecovered by an insulating film 11 h of SiO₂ formed on them. In apredetermined region on the insulating film 11 h, a pad electrode 11 iis formed which covers the ridge and makes ohmic contact with theelectrode 11 g. On the bottom face of the substrate 11 a, a reverse-sideelectrode 11 j of Hf/Al is formed.

As shown in FIG. 4, the pad electrode 11 i of each semiconductor laserelement 11 is electrically connected, via a Au wire 14, to the electrodepattern 12 b on the heat spreader 12. The reverse-side electrode 11 j(see FIG. 5) of each semiconductor laser element 11 is electricallyconnected, via an unillustrated solder layer or the like, to theelectrode pattern 12 a. The width of the light emitting portion 11 k(see FIG. 7) of the semiconductor laser element 11 is defined by theridge width (W11 a in FIG. 5) of the upper clad layer 11 e, and thisridge width is set at, for example, 7 μm. In this case, the width of thelight emitting portion 11 k is about 7 μm.

As shown in FIG. 3, the housing member 13 is formed in the shape of abox having an opening on the laser light exit side. The housing member13 is penetrated by electrode pins 15 a and 15 b for supplying electricpower to the semiconductor laser elements 11. These electrode pins 15 aand 15 b are electrically connected, via metal wires 16, to theelectrode patterns 12 a and 12 b, respectively, on the heat spreader 12.The opening in the housing member 13 is fitted with an unillustratedglass plate, and the inside of the housing member 13 is filled with aninert gas. The housing member 13 may be fitted with heat dissipatingfins or the like (unillustrated), and the housing member 13 may be, forexample, air-cooled. As shown in FIG. 6, at a predetermined position onthe glass plate, the light condensing member 21, which will be describedlater, of the light projecting unit 20 is fixed with a transparentadhesive layer in between. Thus, the laser light emanating from thesemiconductor laser elements 11 enters the light condensing member 21.

When a DC (direct-current) electric current is applied between the padelectrode 11 i and the reverse-side electrode 11 j of the semiconductorlaser element 11, as shown in FIG. 7, laser light spreading ellipticallyin the X direction (the width direction of the semiconductor laserelement 11) and in the Y direction (the thickness direction of thesemiconductor laser element 11) emanates from the light emitting portion11 k. The elliptical light projected on an XY plane perpendicular to thetravel direction (the Z direction) of the laser light has a lightintensity distribution that is Gaussian both in the X and Y directions.The light intensity distribution has, in the X direction, afull-width-at-half-maximum (θx) of about 10 degrees and, in the Ydirection, a full-width-at-half-maximum (θy) of about 20 degrees. Thus,the laser light has, in the Y direction, a spread angle about twice aslarge as that in the X direction. Thus, the laser light travels whilespreading in the X direction as a minor-axis direction and in the Ydirection as a major-axis direction.

When the laser generating device 10 is supplied with an electric powerof about 57 W, the laser generating device 10 yields an output of about9.4 W. At that time, the illuminance at the maximum illuminance spot at25 m ahead of the light projection apparatus 1 is about 120 lux (lx),and the luminous flux emitted outside via a reflecting member 23, whichwill be described later, is about 530 lumens (lm).

As shown in FIG. 1, the light projecting unit 20 includes a lightcondensing member 21 which is disposed on the laser light exit side ofthe laser generating device 10 (the semiconductor laser elements 11) andwhich guides the laser light from the laser generating device 10 whilecondensing it, a fluorescent member 22 which converts at least part ofthe laser light emanating from the light condensing member 21 to emitfluorescence, a reflecting member 23 (light projecting member) whichreflects the fluorescence emanating from the fluorescent member 22 in apredetermined direction (direction A), a fitting member 24 to which thefluorescent member 22 is fixed, and a filter member 25 which is disposedat an opening of the reflecting member 23.

The light condensing member 21 is formed as a member that transmitslight. Examples of the material for the light condensing member 21include glass, such as borosilicate crown glass (BK7) and artificialquartz, and resin. As shown in FIG. 8, the light condensing member 21includes a light entrance face 21 a through which the laser lightemanating from the semiconductor laser elements 11 enters; a light exitface 21 b through which the laser light exits; and a top face 21 c, abottom face 21 d, and a pair of side faces 21 e which are locatedbetween the light entrance face 21 a and the light exit face 21 b.

The light entrance face 21 a is formed as, for example, a substantiallyrectangular flat surface. The light exit face 21 b is formed as, forexample, a substantially rectangular flat surface, and has a smallerarea than the light entrance face 21 a. Thus, the light condensingmember 21 is formed in a shape that tapers off both in the widthdirection (direction C) and in the thickness direction (direction D).Specifically, as shown in FIGS. 9 and 10, the light entrance face 21 ahas a height (H21 a) of about 0.96 mm and a width (W21 a) of about 10.51mm; the light exit face 21 b has a height (H21 b) of about 0.34 mm and awidth (W21 b) of about 1.19 mm. Thus, the length (W21 b) of the lightexit face 21 b in direction C (a first direction) is three times or moreas great as the length (H21 b) of the light exit face 21 b in directionD (a second direction). The light entrance face 21 a and the light exitface 21 b may be coated with an unillustrated anti-reflection (AR) film.In the first embodiment, in a case where the light exit face 21 b of thelight condensing member 21 and the irradiated region on the fluorescentmember 22 are rectangular, the direction in which their longer endsextend is taken as a “first direction” according to the invention. Thatis, the direction in which the longest of the sides of the light exitface 21 b and of the irradiated region is taken as a “first direction”according to the invention. Put another way, a “first direction”according to the invention may be defined as the direction that isperpendicular to the light projection direction (direction A) and thatis simultaneously horizontal. On the other hand, a “second direction”according to the invention may be defined as the direction that isperpendicular to the “first direction” and that is simultaneouslyparallel to the surface of the fluorescent member.

The light exit face 21 b may be formed as a coarse surface like thesurface of ground glass or a so-called moth-eye surface. This, asexperimentally verified, greatly improved the efficiency with whichlaser light is taken out of the light condensing member 21 through thelight exit face 21 b. In a case where the light exit face 21 b is a flatsurface, when the laser light reaches the light exit face 21 b insidethe light condensing member 21, part of it is reflected on the innerside of the light exit face 21 b and thus cannot be taken out. Bycontrast, forming the light exit face 21 b as a coarse surface like thesurface of ground glass or a so-called moth-eye surface helps suppressreflection on the inner side of the light exit face 21 b, and thus makesit possible to take out light efficiently.

The top face 21 c and the bottom face 21 d are formed in the same shape,and the two side faces 21 e are formed in the same shape. The top face21 c, the bottom face 21 d, and the side faces 21 e all have a length(L21) of about 50 mm.

The angles (θ21 c and θ21 d) of the top face 21 c and the bottom face 21d, respectively, with respect to the light entrance face 21 a are largerthan the angle (θ21 e) of the side faces 21 e with respect to the lightentrance face 21 a.

The top face 21 c, the bottom face 21 d, and the side faces 21 e have afunction of reflecting the laser light that has entered through thelight entrance face 21 a to guide it to the light exit face 21 b.

Now, how the laser light that has entered the light condensing member 21travels will be described briefly. As shown in FIGS. 11 and 12, thelaser light emanating from the semiconductor laser elements 11 travelswhile spreading in the major- and minor-axis directions, and enters thelight condensing member 21 through the light entrance face 21 a. Thelaser light is then subjected to repeated total reflection on the topface 21 c, the bottom face 21 d, and the side faces 21 e so that it is,while being condensed, guided to the light exit face 21 b; the laserlight then exits through the light exit face 21 b. Thus, the lightcondensing member 21 has a function of guiding the laser light that hasentered through the light entrance face 21 a to the light exit face 21 bwhile altering the travel direction of the laser light inside the lightcondensing member 21. The laser light emanating from the semiconductorlaser elements 11 has a larger spread angle in the major-axis directionthan in the minor-axis direction, and thus the total reflectioncondition is more difficult to fulfill on the top face 21 c and thebottom face 21 d. To cope with this, the angles (θ21 c and θ21 d; seeFIG. 10) of the top face 21 c and the bottom face 21 d with respect tothe light entrance face 21 a is made larger than the angle (θ21 e; seeFIG. 9) of the side faces 21 e with respect to the light entrance face21 a, so that the total reflection condition is easier to fulfill on thetop face 21 c and the bottom face 21 d.

As shown in FIG. 13, arranging the semiconductor laser elements 11 suchthat their respective laser light emission directions (the directions ofthe optical axes of the laser light they emit) point to about the centerof the light exit face 21 b of the light condensing member 21 isparticularly effective, because doing so makes the total reflectioncondition easier to fulfill on the side faces 21 e. In a case where thesemiconductor laser elements 11 are arranged such that their respectivelaser light emission directions point to about the center of the lightexit face 21 b, as shown in FIG. 14, the light entrance face 21 a may beformed so as to be perpendicular to those laser light emissiondirections. This helps suppress lowering in the efficiency with whichlaser light enters the light condensing member 21. The light condensingmember 21 is not limited to one that guides light by exploiting totalreflection, but may instead be one that guides light by exploitingsimple reflection.

As shown in FIGS. 15 to 17, the light condensing member 21 may bechamfered at edges. Specifically, the light condensing member 21 may begiven, on a plane perpendicular to its light guide direction, a crosssection in the shape of a rectangle chamfered at corners. In that case,as shown in FIGS. 15 and 16, the light condensing member 21 may beflat-chamfered at edges (corners in the cross section); instead, asshown in FIG. 17, the light condensing member 21 may be round-chamferedat edges. The light guide direction of the light condensing member 21denotes the direction pointing from the center of the light entranceface 21 a to the center of the light exit face 21 b. Giving the lightcondensing member 21, on a plane perpendicular to its light guidedirection, a cross section in the shape of a rectangle chamfered atcorners makes it possible to suppress scattering of laser light at edges(corners in the cross section) of the light condensing member 21. Thishelps suppress leakage of laser light out of the light condensing member21, and thus helps improve the efficiency of use of laser light.

In this embodiment, the light intensity distribution of the laser lighton the light exit face 21 b of the light condensing member 21 is even asshown in FIG. 18. That is, the light intensity distribution of the laserlight emanating from the light exit face 21 b is not Gaussian. Thishelps prevent excessive light density in part of the irradiated face 22a, which will be described later, of the fluorescent member 22. In thisway, it is possible to prevent heat-induced deterioration, anddeterioration through a light-induced chemical reaction, of the phosphorand binder contained in the fluorescent member 22.

As shown in FIG. 19, the light condensing member 21 is inclined indirection B (the direction opposite to the light projection direction(the predetermined direction, direction A)). Moreover, between the lightexit face 21 b of the light condensing member 21 and the irradiated face22 a of the fluorescent member 22, a gap (space) is formed. The lightprojection direction is the direction pointing to the spot, for exampleat 25 m ahead of the light projection apparatus 1, that is to beilluminated most, and is the direction pointing to, for example, themaximum illuminance spot at 25 m ahead of the center of the opening ofthe reflecting face 23 a.

The fluorescent member 22 has an irradiated face 22 a which isirradiated with laser light. The rear face (the face opposite from theirradiated face 22 a) of the fluorescent member 22 makes contact withthe support plate 26, which is made of aluminum. The fluorescent member22 is formed by being deposited on the support plate 26, for example, byelectrophoresis. The support plate 26 has a width of about 10 mm, alength of about 10 mm, and a thickness of about 1 mm. The fluorescentmember 22 has a width of about 10 mm, a length of about 10 mm, and aneven thickness of about 0.1 mm. As shown in FIG. 20, a central part ofthe irradiated face 22 a of the fluorescent member 22 is irradiated withthe laser light condensed through the light condensing member 21. Thelength of the light exit face 21 b of the light condensing member 21 indirection C is three times or more (here, about 3.5 times) as great asthe length of the light exit face 21 b in direction D. Thus, as shown inFIG. 21, the length (Lc) in direction C of the irradiated region S, thatis, the central part of the irradiated face 22 a which is irradiatedwith laser light, is tree times or more (here, about 3.5 times) as greatas the length (Ld) of the irradiated region S in direction D. Thus, thefluorescent member 22 is excited in a substantially rectangular areathat is elongate in direction C. In other words, the fluorescent member22 is excited with a distribution spreading in the direction (directionC) perpendicular to the light projection direction (direction A) aboutthe focus F23, which will be described later, of the reflecting face 23a. Thus, fluorescent emanates from a substantially rectangular region. Afluorescent member 22 may instead be used that only has an area as largeas the area irradiated with laser light, so that the entire irradiatedface 22 a of the fluorescent member 22 is irradiated with laser light.

The fluorescent member 22 is formed by use of particles of three kindsof phosphors (fluorescent or phosphorescent substances) that convert,for example, blue-violet light (exciting light) into red, green, andblue light respectively and emit the results. An example of the phosphorthat converts blue-violet light into red light is CaAlSiN₃:Eu. Anexample of the phosphor that converts blue-violet light into green lightis β-SiAlON:Eu. An example of the phosphor that converts blue-violetlight into blue light is (Ba,Sr)MgAl₁₀O₁₇:Eu. These phosphors are boundtogether by an inorganic binder (such as silica or TiO₂). The red,green, and blue fluorescence emanating from the fluorescent member 22mixes to produce white light. Here, red light is light with a centerwavelength of, for example, about 640 nm, green light is light with acenter wavelength of, for example, about 520 nm, and blue light is lightwith a center wavelength of, for example, about 450 nm.

As shown in FIG. 1, the fluorescent member 22 is disposed in a region onthe reflecting member 23 which includes the focus F23 of the reflectingface 23 a, and the center of the irradiated face 22 a of the fluorescentmember 22 approximately coincides with the focus F23 of the reflectingface 23 a. The fluorescent member 22 may be disposed near the focus F23of the reflecting face 23 a on the reflecting member 23. As shown inFIG. 19, the irradiated face 22 a of the fluorescent member 22 isinclined upward in the light projection direction (direction A).

As shown in FIG. 22, the reflecting face 23 a of the reflecting member23 is disposed so as to face the irradiated face 22 a of the fluorescentmember 22. The reflecting face 23 a is formed so as to include, forexample, part of a paraboloid. Specifically, the reflecting face 23 a isformed in the shape of a paraboloid that is split on the planeperpendicular to (crossing) the axis through its vertex V23 and focusF23 and that is further split on the plane parallel to the axis throughthe vertex V23 and focus F23. As shown in FIGS. 22 and 23, thereflecting face 23 a has a depth (length in direction B) of about 30 mm,and is formed substantially in a semicircular shape with a radius ofabout 30 mm as seen from the light projection direction (direction A).

The reflecting face 23 a has a function of reflecting the light from thefluorescent member 22 in a predetermined direction (direction A). Thelight emanating from the fluorescent member 22 at the focus F23 of thereflecting face 23 a is formed into parallel light by the reflectingface 23 a, whereas the light emanating from the fluorescent member 22 ata position deviated from the focus F23, for example, in direction C isprojected in a state spread in direction C by the reflecting face 23 a.In a part of the reflecting member 23 deviated from the center of thefluorescent member 22 in direction B, a through hole 23 b is formed. Inthe through hole 23 b, a tip-end part of the light condensing member 21is inserted.

The reflecting member 23 may be formed of metal, or may be formed bycoating the surface of resin with a reflective film.

To the reflecting member 23, a fitting member 24 is fixed. Preferably,the top face 24 a of the fitting member 24 is formed so as to have afunction of reflecting light. The fitting member 24 is formed of metalwith good thermal conductivity, such as Al or Cu, so as to have afunction of dissipating the heat generated in the fluorescent member 22.On the top face 24 a of the fitting member 24, a fitting portion 24 b onwhich to fix the fluorescent member 22 and the support plate 26 isformed integrally. As shown in FIG. 19, the fitting face 24 c of thefitting portion 24 b is inclined upward in the light projectiondirection (direction A). Preferably, on the bottom face of the fittingmember 24, heat dissipating fins (unillustrated) are provided.

As shown in FIG. 1, the opening (the end in direction A) of thereflecting member 23 is fitted with a filter member 25 which shields(absorbs or reflects) exciting light (light with a wavelength of about405 nm) but transmits the fluorescence (red, green, and blue light)resulting from the wavelength conversion by the fluorescent member 22.Specifically, the filter member 25 may be formed of a glass materialsuch as, for example, ITY-418 manufactured by Isuzu Glass Co., Ltd.,which absorbs light with wavelengths of 418 nm or less and transmitslight with wavelengths more than 418 nm, or, for example, L42manufactured by Hoya Corporation, which absorbs light with wavelengthsof 420 nm or less and transmits light with wavelengths more than 420 nm.Providing the filter member 25 at the opening of the reflecting member23 helps suppress leakage of laser light.

Next, with reference to FIG. 24, the projection pattern of the lightemitted from the light projection apparatus 1 will be described. FIG. 24illustrates, assuming that a virtual screen is disposed at 25 m ahead ofthe light projection apparatus 1, a light projection pattern P on thevirtual screen. The light projection pattern P obtained by projection offluorescence by the reflecting member 23 had an elliptical shape withthe length (Lpc) in the horizontal direction (direction C) three to fourtimes as great as the length (Lpd) in the up-down direction (directionD). That is, a laterally elongate light projection pattern P wasobtained. A laterally elongate light projection pattern P like this is,in a case where the light projection apparatus 1 is used as a headlampof an automobile, necessary to efficiently illuminate the center of aroad along with the side walks at left and right as well as road signs.In a case where the light exit face 21 b of the light condensing member21 has the same length in directions C and D, the light projectionpattern P has a circular shape with the same length in the horizontaland up-down directions.

In this embodiment, as described above, the length Lc of the irradiatedregion S in direction C is greater than the length Ld of the irradiatedregion S in direction D. Thus, the fluorescent member 22 is excited inan area elongate in direction C. Accordingly, when the light emanatingfrom fluorescent member 22 is reflected outside by the reflecting member23, it is possible to obtain a light projection pattern P that iselongate in direction C (elliptical).

When, as described above, the length (width W21 b) of the light exitface 21 b of the light condensing member 21 in direction C is madegreater than the length (height H21 b) of the light exit face 21 b indirection D, it is easy to make the length Lc of the irradiated region Sof the fluorescent member 22 in direction C greater than the length Ldof the irradiated region S in direction D. Moreover, when the light exitface 21 b of the light condensing member 21 is formed to have a smallerarea than the light entrance face 21 a, the laser light that has enteredthrough the light entrance face 21 a exits through the light exit face21 b in a condensed state. This helps increase the density of the laserlight emanating from the light condensing member 21.

Moreover, as described above, the length (width W21 b) of the light exitface 21 b in direction C is three times or more as great as the length(height H21 b) of the light exit face 21 b in direction D. Thus, it ispossible to make the length Lc of the irradiated region S in direction Cthree times or more as great as the length Ld of the irradiated region Sin direction D. In this way, it is possible to set the ratio of thelength (Lpc) of the light projection pattern P in direction C to itslength (Lpd) in direction D at about three or more. For example, inheadlamps for automobiles, the aspect ratio of a proper light projectionpattern P is about 1 to 1:4; thus, when used as a headlamp of anautomobile, the light projection apparatus 1 can illuminate aheadproperly.

This embodiment is characterized in that, in a system that projectslight obtained by exciting a fluorescent member with laser light, thefluorescent member is excited in a laterally elongate area (in a shapeelongate in a predetermined direction) so that laterally elongate lightis projected, and is further characterized in that, for more favorableimplementation, a light guide member (light condensing member) having alaterally elongate light exit face is used.

Moreover, providing the reflecting member 23 as described above makes iteasy to project the light emanating from the fluorescent member 22 in adesired direction.

Moreover, forming the light exit face 21 b as a coarse surface or amoth-eye surface as described above helps reduce reflection on the innerside of the light exit face 21 b, and thus makes it possible to take outlight efficiently.

Second Embodiment

As a second embodiment, with reference to FIG. 25, a description willnow be given of a case where, unlike in the first embodiment describedabove, the fluorescence emanating from the rear face (the face oppositefrom the irradiated face 22 a) of the fluorescent member 22 is reflectedon the reflecting member 23.

In a light projection apparatus 101 according to the second embodimentof the invention, as shown in FIG. 25, a light projection unit 120includes a light condensing member 21, a fluorescent member 22, areflecting member 23, and a subsidiary reflecting member 127.

The fluorescent member 22 has a thickness of about 0.1 mm to about 1 mm,and the irradiated face 22 a and the rear face of the fluorescent member22 are formed in the same size as the light exit face 21 b of the lightcondensing member 21. The fluorescent member 22 is fixed on the lightexit face 21 b of the light condensing member 21. Thus, as in the firstembodiment described previously, the fluorescent member 22 is excited ina rectangular area elongate in direction C (in FIG. 25, the directionperpendicular to the plane of paper). The length of the irradiatedregion (the entire irradiated face 22 a) of the fluorescent member 22 indirection C is three times or more (here, about 3.5 times) as large asthe length of the irradiated region in direction D. Fluorescenceemanates from a rectangular region.

In this embodiment, the fluorescent member 22 has a lower density ofphosphor particles than that in the first embodiment describedpreviously, and when irradiated with laser light, emits fluorescencefrom the rear face (the face opposite from the irradiated face 22 a).The fluorescent member 22 may emit fluorescence also from a side face(any of the faces that connect between the irradiated face 22 a and therear face).

The reflecting face 23 a of the reflecting member 23 is formed in theshape of a paraboloid that is split on the plane perpendicularly to(crossing) the axis through its vertex and focus. The reflecting face 23a has a depth (length in direction B) of about 15 mm, and is formed in acircular shape with a radius of about 15 mm as seen from the lightprojection direction (direction A).

In this light projection apparatus 101, as in the light projectionapparatus 1 of the first embodiment described previously, the lightprojection pattern P of the fluorescence projected by the reflectingmember 23 has an elliptical shape with its length in horizontaldirection (direction C) three to four times as large as its length inthe up-down direction (direction D).

The subsidiary reflecting member 127 is disposed in front of thefluorescent member 22. The subsidiary reflecting member 127 is formed ina shape that includes part of a spherical face, and is formed in acircular shape with a diameter of about 5 mm as seen from the lightprojection direction (direction A). The subsidiary reflecting member 127serves to reflect the fluorescence that tends to travel outside withoutstriking the reflecting member 23, and the laser light that has passedthrough the fluorescent member 22, to direct it back to the fluorescentmember 22. The light directed back to the fluorescent member 22 isscattered, or converted into fluorescence, by the fluorescent member 22,and then emanates from the fluorescent member 22 again; this time, thelight emanates from the rectangular region.

In other respects, the structure and benefits of the second embodimentare similar to those of the first embodiment described previously.

Third Embodiment

As a third embodiment, with reference to FIGS. 26 to 29, a descriptionwill be given of a case where, unlike in the first and secondembodiments described above, the light exit face 21 b of the lightcondensing member 21 is formed in an elongate hexagonal shape.

In the light condensing member 21 in this embodiment, as shown in FIG.26, the light entrance face 21 a and the light exit face 21 b are formedin an elongate hexagonal shape. Specifically, the light entrance face 21a has a height (H21 a) of about 3 mm and a width (W21 a) of about 15 mm.The light exit face 21 b has a height (H21 b) of about 2 mm and a width(W21 b) of about 6 mm. The top face 21 c and the bottom face 21 d have,at their light exit face 21 b side end, a width (W21 c) of about 2 mm.

Thus, when laser light is shone onto the fluorescent member 22, theirradiated region S on the fluorescent member 22 appears as shown inFIG. 27, and the length (Lc) of the irradiated region S in direction Cis three times or more (here, about three times) as large as the length(Ld) of the irradiated region S in direction D. The light intensitydistribution on the fluorescent member 22 in direction C is as shown inFIG. 28.

When the light condensing member 21 of this embodiment is used, thelight intensity distribution of the fluorescence at 25 m ahead of thelight projection apparatus is as plotted by the solid line in FIG. 29.In FIG. 29, the broken line plots the light intensity distribution ofthe fluorescence in a case where the light exit face 21 b of the lightcondensing member 21 is formed in the shape of a rectangle with a heightof about 2 mm and a width of about 6 mm. Forming the light exit face 21b in an elongate hexagonal shape (the solid-line plot in FIG. 29), ascompared with forming the light exit face 21 b in a rectangular shape(the broken-line plot in FIG. 29), helps increase the light intensity ina 2 m-wide front region R1 (a region corresponding to the center of aroad) and reduce the light intensity in peripheral regions R2 (regionscorresponding to side walks, roadside trees, road signs, etc.). That is,forming the light exit face 21 b in an elongate hexagonal shape makes itpossible to spread the light projection pattern in the horizontaldirection (direction C), and to reduce the light unnecessarilydistributed to the peripheral regions R2.

In the third embodiment, the direction in which the longest of the linestraversing the light exit face 21 b and the irradiated region extends isdefined as a “first direction” according to the invention. Putotherwise, a “first direction” according to the invention is thedirection that is perpendicular to the light projection direction(direction A) and that is simultaneously horizontal. On the other hand,a “second direction” according to the invention can be said to be thedirection that is perpendicular to the “first direction” and that issimultaneously parallel to the surface of the fluorescent member.

In other respects, the structure and benefits of the third embodimentare similar to those of the first and second embodiments describedpreviously.

Fourth Embodiment

Next, with reference to FIGS. 30 to 33, the structure of a lightprojection apparatus 201 according to a fourth embodiment of theinvention will be described.

In the light projection apparatus 201 according to the fourth embodimentof the invention, as shown in FIG. 30, a light projecting unit 220includes a light condensing member 21, a fluorescent member 22, areflecting member 23, and a base plate 228 which supports thefluorescent member 22.

As shown in FIG. 31, in the light condensing member 21 in thisembodiment, the light entrance face 21 a is formed in a rectangularshape, and the light exit face 21 b is formed in the shape of aninverted trapezoid. Specifically, the light entrance face 21 a has aheight (H21 a) of about 3 mm and a width (W21 a) of about 10 mm. Thelight exit face 21 b has a height (H21 b) of about 3 mm and a width (W21b) of about 3 mm. The top face 21 c has, at its light exit face 21 bside end, a width (W21 c) of about 3 mm, and the bottom face 21 d has,at its light exit face 21 b side end, a width (W21 d) of about 1 mm.

As shown in FIG. 30, the fluorescent member 22 is disposed at a distanceof about 1.9 mm from the vertex of the reflecting face 23 a of thereflecting member 23, and has a diameter of about 7.5 mm. Thecircumferential face of the fluorescent member 22 makes contact with thereflecting face 23 a of the reflecting member 23. As shown in FIG. 32,the fluorescent member 22 is disposed in a region on the reflectingmember 23 which includes the focus F23 of the reflecting face 23 a, andthe center of the irradiated face 22 a of the fluorescent member 22approximately coincides with the focus F23 of the reflecting face 23 a.The fluorescent member 22 is provided on the base plate 228. Thefluorescent member 22 is formed, for example, by applying and thencuring resin containing phosphor particles to the base plate 228.

As shown in FIG. 30, the base plate 228 has a function of transmittingthe fluorescence emanating from the fluorescent member 22, and is fixedto the reflecting face 23 a of the reflecting member 23.

The reflecting face 23 a of the reflecting member 23 is formed in theshape of a paraboloid that is split on the plane perpendicular to(crossing) the axis through its vertex and focus. The reflecting face 23a has a depth (length in direction B) of about 30 mm, and is formedsubstantially in a circular shape with a radius of about 15 mm as seenfrom the light projection direction (direction A).

In this embodiment, when laser light is shone onto the fluorescentmember 22, as shown in FIG. 32, the irradiated region S on thefluorescent member 22 has the shape of an inverted trapezoid.Specifically, the irradiated region S has a height (Hs) of about 3 mm,the upper side of the irradiated region S has a width (Ws1) of about 3mm, and the lower side of the irradiated region S has a width (Ws2) ofabout 1 mm.

The center of the irradiated region S is located at a position deviatedfrom the focus F23 of the reflecting face 23 a. Specifically, the length(Ls1) from the focus F23 to the end of the irradiated region S indirection D (third direction) is smaller than one-half of the length(Ls2 (=Ws1)) of the irradiated region S in direction C (fourthdirection). That is, the irradiated region S is formed so as to spreadin the left-right direction and in the downward direction (toward theground) with respect to the focus F23.

Thus, the light projection pattern at 25 m ahead of the light projectionapparatus 201 is as shown in FIG. 33. Specifically, the light projectionpattern P does not spread in the upward direction, but spreads in theleft-right direction (in the horizontal direction) and in the downwarddirection. Thus, it is possible to illuminate an area around a roadwhile reducing unnecessary illumination toward the sky (upward). Thelight intensity in a front region R1 with a diameter of about 2 m (aregion corresponding to the center of a road) is high, and the lightintensity in peripheral regions R2 (regions corresponding to side walks,roadside trees, road signs, etc.) is low.

In other respects, the structure of the fourth embodiment is similar tothat of the first to third embodiment described previously.

In this embodiment, as described above, the length (Ls1) from the focusF23 of the reflecting face 23 a to the end of the irradiated region S indirection D is smaller than one-half of the length (Ls2) of theirradiated region S in direction C, which is perpendicular to directionD. Thus, the distance from the end of the irradiated region S indirection D to the focus F23 of the reflecting face 23 a is shorter thanthe distance from the end of the irradiated region S in direction C tothe focus F23 of the reflecting face 23 a. Thus, it is possible to makethe length (Lpd) of the light projection pattern P in direction Dsmaller than the length (Lpc) of the light projection pattern P indirection C. That is, it is possible to obtain a light projectionpattern P that is elongate in direction C (elliptical).

In other respects, the benefits of the fourth embodiment are similar tothose of the first to third embodiment described previously.

Fifth Embodiment

Next, with reference to FIGS. 34 to 38, the structure of a lightprojection apparatus 301 according to a fifth embodiment of theinvention will be described.

In the light projection apparatus 301 according to the fifth embodimentof the invention, as shown in FIG. 34, a light projecting unit 320includes a light condensing member 21, a fluorescent member 22, areflecting member 23, a support member 329 which supports thefluorescent member 22, and a lens (projection lens) 330.

In the light condensing member 21 in this embodiment, as shown in FIG.35, the light entrance face 21 a is formed in a rectangular shape.Unlike in the embodiments described previously, the light exit face 21 bis formed so as to be asymmetric in the left-right direction, and isformed in a shape corresponding to a light projection pattern P of a lowbeam (a passing-by headlamp). Specifically, the light entrance face 21 ahas a height (H21 a) of about 3 mm and a width (W21 a) of about 10 mm.Moreover, the light exit face 21 b is formed in a shape having an upperright part thereof cut out, so as to have different heights at left andright. Here, left denotes the left side (opposite to direction C) of anautomobile pointing in its travel direction, and corresponds to theright side in FIG. 35; right denotes the right side (in direction C) ofan automobile pointing in its travel direction, and corresponds to theleft side in FIG. 35. Of the light exit face 21 b, a left part has aheight (HL21 b) of about 1.9 mm, and a right part has a height (HR21 b)of about 1.5 mm. The bottom face 21 d has, at its light exit face 21 bside end, a width (W21 d) of about 6 mm. In FIG. 35, the width W21 e isabout 3 mm, the width W21 f is about 2.6 mm, and the width W21 g isabout 0.4 mm.

In this embodiment, the light intensity distribution of the laser lighton the light exit face 21 b of the light condensing member 21 is even asin the first embodiment described previously.

As shown in FIG. 34, the fluorescent member 22 is disposed in a regionon the reflecting member 23 which includes the first focus F23 a of thereflecting face 23 a. The fluorescent member 22 is provided on abar-form support member 329 made of, for example, metal. The fluorescentmember 22 is formed, for example, by applying and then curing resincontaining phosphor particles to the support member 329. The supportmember 329 is fixed on the reflecting face 23 a of the reflecting member23. The support member 329 may instead be formed of a material, such asglass or resin, that transmits the light emanating from the fluorescentmember 22.

In this embodiment, when laser light is shone onto the fluorescentmember 22, the irradiated region S on the fluorescent member 22 appearsasymmetric in the left-right direction as shown in FIG. 36.Specifically, like the light exit face 21 b of the light condensingmember 21, the irradiated region S is formed so that its projectionimage is a light projection pattern P of a low beam (a passing-byheadlamp), and has a shape having an upper right portion thereof cutout. Moreover, in the irradiated region S, lines Sm1 and Sm2 and a pointSe are formed whose projection images are cut-off lines M1 and M2 and anelbow point E, which will be described later, in the light projectionpattern P. These lines Sm1 and Sm2 form part of the edges of theirradiated region S. The point Se is the intersection between the linesSm1 and Sm2.

As shown in FIG. 34, the reflecting face 23 a of the reflecting member23 is formed so as to include part of an ellipsoid. Specifically, thereflecting face 23 a is formed in the shape of an ellipsoid that issplit on the plane perpendicular to (crossing) the axis through itsfirst focus F23 a and second focus F23 b. The reflecting face 23 a has adepth (length in direction B) of about 30 mm, and is formed in acircular shape with a radius of about 15 mm as seen from the lightprojection direction (direction A).

The first focus F23 a of the reflecting face 23 a of the reflectingmember 23 is located so as to approximately coincide with the point Se(the intersection between the lines Sm1 and Sm2) in the irradiatedregion S on the fluorescent member 22. In other words, the first focusF23 a is located at a position in the irradiated region S from where theelbow point E, which will be described later, in the light projectionpattern P is projected.

The lens 330 is disposed in front of the reflecting member 23. The lens330 has a radius of about 15 mm. The focus F330 of this lens 330approximately coincides with the second focus F23 b of the reflectingface 23 a of the reflecting member 23. The lens 330 may be a planoconvexlens, a biconvex lens, or a lens of any other shape.

In this embodiment, the light emanating from the irradiated region S onthe fluorescent member 22 is reflected on the reflecting face 23 a ofthe reflecting member 23, passes through the second focus F23 b of thereflecting face 23 a, and is projected by the lens 330. The lightprojection pattern P at 25 m ahead of the light projection apparatus 301has, as shown in FIG. 37, a shape that reflects the irradiated region S.

Specifically, the light projection pattern P does not spread in aright-upward direction but spreads in the left-right direction(horizontal direction) and in the downward direction. In this lightprojection pattern P, illuminance sharply changes at the cut-off linesM1 and M2, so that the region above the cut-off lines M1 and M2 is notirradiated with illumination light. That is, the light projectionpattern P is formed in a shape having an upper right part thereof cutout. This helps suppress glare light that reaches a passing-by driver.Moreover, illuminance is highest in a region R101 (a region right aheadof an automobile) near the elbow point E, which is the intersectionbetween the cut-off lines M1 and M2, and decreases away from the regionR101. Thus, illuminance is increasingly low in regions R101, R102, andR103 in this order.

In left-hand traffic countries such as Japan, a low beam of anautomobile is required to have a light projection pattern P having anupper right part thereof cut out as shown in FIG. 38. The cut-off linesM1 and M2 need to be such that illuminance changes sharply at them sothat no glare light reaches a passing-by driver.

As described above, the light projection apparatus 301 of thisembodiment provides a satisfactory light projection pattern P asrequired in a low beam of an automobile.

In other respects, the structure of the fifth embodiment is similar tothat of the first to fourth embodiments described previously.

In this embodiment, as described above, the light exit face 21 b has ashape that is asymmetric in the left-right direction. This makes it easyto give the irradiated region S a shape that is asymmetric in theleft-right direction, and thus it is easy to give the light projectionpattern P a shape that is asymmetric in the left-right direction.

Moreover, as described above, the first focus F23 a of the reflectingface 23 a of the reflecting member 23 is located on the lines Sm1 andSm2 on the irradiated region S from where the cut-off lines M1 and M2 inthe light projection pattern P are projected. This is particularlyeffective because it permits a sharp change in illuminance at thecut-off lines M1 and M2.

Moreover, as described above, the first focus F23 a of the reflectingface 23 a of the reflecting member 23 is located at a position on theirradiated region S from where the elbow point E in the light projectionpattern P is projected. This is more effective because it permits asharp change in illuminance near the elbow point E. Moreover, thehighest illuminance is obtained near the elbow point. That is, a region(region R101) right ahead of an automobile can be illuminated with thehighest illuminance. Moreover, by locating the first focus F23 a at aposition on the irradiated region S (the center of the irradiated regionS in the left-right direction) from which the elbow point E in the lightprojection pattern P is projected, it is possible to make a lower partof the light projection pattern P substantially symmetric in theleft-right direction.

Moreover, as described above, the light emanating from the irradiatedregion S is reflected on the reflecting face 23 a, passes through thesecond focus F23 b of the reflecting face 23 a, and is projected by thelens 330. Here, since the second focus F23 b of the reflecting face 23 acoincides with the focus F330 of the lens 330, it is easier for thelight projection pattern P formed by the lens 330 to reflect the shapeof the irradiated region S. Projecting light by use of the lens 330, ascompared with projecting light with the reflecting member 23 withoutproviding the lens 330, makes it easier for the light projection patternP to reflect the shape of the irradiated region S. Moreover, providingthe reflecting member 23, compared with projecting light with the lens330 without providing the reflecting member 23, makes it possible to usemore of the light emanating from the fluorescent member 22 asillumination light. This helps improve the efficiency of use of light.

In other respects, the benefits of the fifth embodiment are similar tothose of the first to fourth embodiments described previously.

Sixth Embodiment

Next, with reference to FIGS. 39 and 40, the structure of a lightprojection apparatus 401 according to a sixth embodiment of theinvention will be described.

In the light projection apparatus 401 according to the sixth embodimentof the invention, as shown in FIG. 39, a light projection unit 420includes a light condensing member 21, a fluorescent member 22, asupport member 329 which supports the fluorescent member 22, and a lens330.

The support member 329 is formed so as to transmit the light emanatingfrom the fluorescent member 22. The support member 329 may instead beformed so as to shield (absorb) only excited light.

The lens 330 is disposed in front of the fluorescent member 22. Thefocus F330 of this lens 330 is located so as to approximately coincidewith the point Se (the intersection between the lines Sm1 and Sm2) inthe irradiated region S on the fluorescent member 22.

As shown in FIG. 40, the light condensing member 21 in this embodimentis disposed as if the light condensing member 21 in the fifth embodimentdescribed previously were rotated by 180 degrees. This is because, inthe light projection apparatus 401, the shape of the irradiated region Son the fluorescent member 22 is reflected, in a state rotated by 180degrees, in the light projection pattern P.

In this light projection apparatus 401, the light emanating from therear face of the reflecting member 23 is projected by the lens 330.

In other respects, the structure of the sixth embodiment is similar tothat of the fifth embodiment described previously.

In this embodiment, as described above, the focus F330 of the lens 330is located in the irradiated region S. Thus, the light projectionpattern P formed by the lens 330 reflects the shape of the irradiatedregion S. Projecting light by use of the lens 330, as compared withprojecting light with the reflecting member 23 without providing thelens 330, makes it easier for the light projection pattern P to reflectthe shape of the irradiated region S.

In other respects, the benefits of the sixth embodiment are similar tothose of the fifth embodiment described previously.

Seventh Embodiment

Next, with reference to FIG. 41, the structure of a light projectionapparatus 501 according to a seventh embodiment of the invention will bedescribed.

In the light projection apparatus 501 according to the seventhembodiment of the invention, as shown in FIG. 41, a light condensingmember 21 is formed in a similar manner to the light condensing member21 in the sixth embodiment described previously.

A reflecting member 23 is formed in a similar manner to the reflectingmember 23 in the first embodiment described previously.

As in the fifth and sixth embodiments described previously, the focusF23 of the reflecting face 23 a of the reflecting member 23 is locatedso as to approximately coincide with the point Se (the intersectionbetween the lines Sm1 and Sm2) in the irradiated region S on thefluorescent member 22.

In this embodiment, the light emanating from the irradiated region S onthe fluorescent member 22 is projected by being reflected on thereflecting face 23 a of the reflecting member 23.

In other respects, the structure of the seventh embodiment is similar tothat of the first embodiment described previously.

The benefits of the seventh embodiment are similar to those of the firstand fifth embodiments described previously.

It should be understood that the first to seventh embodiments presentedabove are in every respect only illustrative and not restrictive. Thescope of the present invention is defined not by the description of thefirst to seventh embodiments presented above but by the appended claims,and encompasses all variations and modifications made within the spiritand scope equivalent to the claims.

For example, although the first to seventh embodiments presented abovedeal with examples where a light projection apparatus according to theinvention is used as a headlamp of an automobile, this is not meant tobe any limitation. A light projection apparatus according to theinvention may be used as a headlamp of an airplane, ship, robot,motorcycle, bicycle, or any other mobile body.

Although the first to seventh embodiments presented above deal withexamples where a light projection apparatus according to the inventionis applied to a headlamp, this is not meant to be any limitation. Alight projection apparatus according to the invention may be applied toa downlight, spotlight, or any other type of light projection apparatus.

Although the first to seventh embodiments presented above deal withexamples where the exciting light is converted into visible light, thisis not meant to be any limitation; the exciting light may instead beconverted into any light other than visible light. For example, a designthat converts the exciting light into infrared light finds applicationin, for example, night vision illumination apparatus for surveillanceCCD cameras.

Although the first to seventh embodiments presented above deal withexamples where the exciting light source (semiconductor laser element)and the fluorescent member are designed to emit white light, this is notmeant to be any limitation. The exciting light source and thefluorescent member may be designed to emit light other than white light.

Although the first to seventh embodiments presented above deal withexamples where a semiconductor laser element is used as the lasergenerator for emitting laser light, this is not meant to be anylimitation; any laser generator other than a semiconductor laser elementmay instead be used.

All specific values mentioned above in connection with the first toseventh embodiments presented above are merely examples, and are notmeant to be any limitation.

In the first to seventh embodiments presented above, the centerwavelength of the laser light emitted by the semiconductor laserelement, and the kind of phosphor used in the fluorescent member, may bechanged as desired. For example, it is possible to use a semiconductorlaser element that emits blue laser light with a center wavelength ofabout 450 nm in combination with a phosphor that converts part of theblue laser light into yellow light. In a case where the exciting light(laser light) is diffused by the fluorescent member sufficiently to besafe, no filter member for shielding the exciting light needs to beprovided. In that case, blue and yellow light produces white light. Oneexample of the phosphor that converts part of blue laser light intoyellow light is (Y_(1-x-y)Gd_(x)Ce_(y))₃Al₅O₁₂ (0.1≦x≦0.55, 0.01≦y≦0.4).This is not meant to be any limitation; the center wavelength of thelaser light emitted by the semiconductor laser element may be selectedas desired within the spectrum ranging from ultraviolet to visiblelight.

Although the first to seventh embodiments presented above deal withexamples where the light exit face of the light condensing member areformed in the shape of a rectangle, elongate hexagon, or the like, thisis not meant to be any limitation. For example, as in a light condensingmember 21 according to a first modified example of the invention shownin FIG. 42, the light exit face 21 b may be formed in an ellipticalshape. The light exit face may be formed to be asymmetric in both theup-down and left-right directions. The shape of the light exit face maybe set such that it produces a desired light projection pattern.

Although the fifth to seventh embodiments presented above deal withexamples where a lens is provided at a predetermined distance from thefluorescent member, this is not meant to be any limitation. For example,as in a light projection apparatus according to a second modifiedexample of the invention shown in FIG. 43, a lens 630 (light projectingmember) may be provided so as to cover the fluorescent member 22. Withthis design, the light emanating from the fluorescent member 22 passesthrough, and is refracted by, the lens 630 to be projected outside,producing an elongate light projection pattern. Or as in a lightprojection apparatus 701 according to a third modified example of theinvention shown in FIG. 44, the hollow space inside the reflecting face23 a of the reflecting member 23 may be filled with resin, glass, or thelike so as to form a lens 730. Or as in the fifth to seventh embodimentspresented above, a projection lens (unillustrated) may be disposed infront of the fluorescent member 22. As a light projecting member, aprism or the like may be used instead of a reflecting member or a lens.

Although the first to seventh embodiments presented above deal withexamples where the reflecting face of the reflecting member is formed aspart of a paraboloid or part of an ellipsoid, this is not meant to beany limitation. The reflecting face may instead be formed as a multiplereflector composed of a number of curved surfaces (such as paraboloids),or as a free-form curved-surface reflector composed of a number ofminuscule flat surfaces provided contiguously.

Although the fifth embodiment presented above deals with an examplewhere the reflecting face 23 a of the reflecting member 23 is formed ina circular shape as seen from the light projection direction (directionA), this is not meant to be any limitation. For example, as in a lightprojection apparatus 801 according to a fourth modified example of theinvention shown in FIG. 45, the reflecting face 23 a of the reflectingmember 23 may be formed so as to include part of an ellipsoid andsubstantially in a semicircular shape as seen from the light projectiondirection. In this light projection apparatus 801, as in the fifthembodiment presented above, the first focus F23 a of the reflecting face23 a of the reflecting member 23 approximately coincides with the pointSe in the irradiated region S on the fluorescent member 22. Moreover,the focus F330 of the lens 330 approximately coincides with the secondfocus F23 b of the reflecting face 23 a of the reflecting member 23. Theupper half of the lens 330 may be omitted.

Although the sixth embodiment presented above deals with an examplewhere no reflecting member 23 is provided and instead the lightemanating from the rear face of the fluorescent member 22 is projectedby the lens 330, this is not meant to be any limitation. For example, asin a light projection apparatus 901 according to a fifth modifiedexample of the invention shown in FIG. 46, the fluorescent member 22 maybe irradiated with laser light from the lens 330 side so that the lightemanating from the irradiated face 22 a of the fluorescent member 22 maybe projected by the lens 330 without the use of a reflecting member 23.

Although the fifth to seventh embodiments presented above deal withexamples where no light shielding plate is used but instead the lightprojection pattern is formed in a shape having an upper right partthereof cut out, this is not meant to be any limitation. For example, alight shielding plate may be provided between a reflecting member (orfluorescent member) and a lens. With this design, illuminance can bechanged more sharply at the edge of the light projection pattern, or amore complicated light projection pattern can be obtained. Forming thelight exit face of the light condensing member in a shape correspondingto a light projection pattern as in the fifth to seventh embodimentsdescribed above makes it possible to set the shape of the irradiatedregion and the shape of the light projection pattern in advance, andthus helps reduce the amount of light shielded by the light shieldingplate. This helps suppress lowering of the efficiency of use of light.

Although the fifth to seventh embodiments presented above deal withexamples where, assuming application in left-hand traffic countries suchas Japan, a light projection pattern having an upper right part thereofcut out is obtained, this is not meant to be any limitation. Forapplication in right-hand traffic countries, the shape of the light exitface of the light condensing member may be reversed in the left-rightdirection to obtain a light projection pattern having an upper left partthereof cut out.

Although the first to seventh embodiments presented above deal withexamples where a plurality of semiconductor laser elements are used asan exciting light source, this is not meant to be any limitation. Asingle semiconductor layer may instead be used as an exciting lightsource. Or a so-called semiconductor laser array provided with aplurality of light emitting portions may be used as an exciting lightsource.

Although the first to seventh embodiments presented above deal withexamples where the laser light that has entered the light condensingmember through the light entrance face is guided to the light exit faceby being reflected on the top, bottom, and side faces, this is not meantto be any limitation. The light condensing member may be formed so thatits refractive index smoothly or gradually decreases radially fromcenter to edge, like a graded-index optical fiber, in order to alter thetravel direction of the laser light inside the light condensing memberso as to guide it to the light exit face.

Although the first to seventh embodiments presented above deal withexamples where the fluorescent member is excited in a laterally elongatearea (in a horizontally elongate shape), this is not meant to be anylimitation. The fluorescent member may be excited, for example, in alongitudinally elongate area (a vertically elongate shape), or may beexcited in an obliquely elongate shape.

The fifth to seventh embodiments presented above deal with exampleswhere, in a light projection apparatus that produces an elongate lightprojection pattern, the focus of the light projecting member is locatedat the edge of the irradiated region. There, as described above,illuminance can be changed sharply at the part (cut-off lines) of thelight projection pattern which corresponds to the edge of the irradiatedregion where the focus of the light projecting member is located. Alsoin a light projection apparatus that produces a light projection patternother than rectangular, locating the focus of the light projectingmember at the edge (or near the edge) of the irradiated region providesa similar effect. Specifically, in a light projection apparatusincluding a fluorescent member which is excited by exciting light and alight projecting member which reflects or transmits the light emanatingfrom the fluorescent member to project it outside, wherein thefluorescent member includes an irradiated region which is irradiatedwith the exciting light and the light projecting member has its focuslocated at or near the edge of the irradiated region, at the part of thelight projection pattern which corresponds to the edge of the irradiatedregion at which the focus of the light projecting member is located,illuminance can be changed sharply. Needless to say, this applies alsoin cases where the exciting light source is a light source other than alaser light source (for example, a light emitting diode).

Eighth Embodiment

Now, with reference to FIGS. 47 to 67, the structure of a light emittingapparatus 1001 according to an eighth embodiment of the invention willbe described. For the sake of simple illustration, not all semiconductorlaser elements 11 are always illustrated.

The light emitting apparatus 1001 according to the eighth embodiment ofthe invention is used as a headlamp for illuminating ahead of, forexample, an automobile or the like. As shown in FIGS. 47 and 48, thelight emitting apparatus 1001 is provided with a laser generating device1010 which functions as a laser light source (exciting light source) anda light projecting unit 1020 which, by using the laser light emanatingfrom the laser generating device 1010, projects light in a predetermineddirection (direction A). In FIG. 48, for the sake of easy understanding,a fitting portion 1024 b, a filter member 1025, and a support plate1026, which will be described later, of the light projecting unit 1020are omitted.

As shown in FIG. 49, the laser generating device 1010 includes aplurality of semiconductor laser elements 11 (laser generators), a heatspreader 12 on which the semiconductor laser elements 11 are mounted,and a metal casing 1013 (housing member) which houses them all. In FIGS.49 and 51, a transparent plate 1017, which will be described later, isomitted.

The semiconductor laser elements 11 and the heat spreader 12 are formedin a similar manner as those in the first embodiment describedpreviously. Specifically, The semiconductor laser elements 11 are, forexample, broad area lasers, and emit laser light that functions asexciting light. The semiconductor laser elements 11 are designed to emitblue-violet laser light with a center wavelength of, for example, about405 nm. The heat spreader 12 is formed, for example, as a flat plate ofaluminum nitride, and is soldered to the bottom face of the housingmember 13.

As shown in FIG. 49, the casing 1013 is formed in the shape of a boxhaving an opening 1013 a on the laser light exit side. The casing 1013is penetrated by electrode pins 15 a and 15 b for supplying electricpower to the semiconductor laser elements 11. These electrode pins 15 aand 15 b are electrically connected, via metal wires 16, to theelectrode patterns 12 a and 12 b, respectively, on the heat spreader 12.The opening 1013 a in the casing 1013 is fitted with a transparent plate1017 (see FIG. 50) that is made of glass or the like and has a functionof transmitting laser light, and the inside of the casing 1013 is filledwith an inert gas. The casing 1013 may be fitted with heat dissipatingfins or the like (unillustrated), and the casing 1013 may be, forexample, air-cooled.

As shown in FIGS. 51 and 52, at a predetermined position on thetransparent plate 1017 (see FIG. 52), a light condensing member 1021,which will be described later, of the light projecting unit 1020 isfixed (held) with an adhesive layer 1018 (see FIG. 52) in between thathas a function of transmitting laser light. Thus, the laser lightemanating from the semiconductor laser elements 11 enters the lightcondensing member 1021. As the adhesive layer 1018, for example,Optokleb (a trademark) manufactured by Adell Corporation may be used.Preferably, the adhesive layer 1018 is provided over the entire surfaceof the light entrance face 1021 a, which will be described later, of thelight condensing member 1021, in which case the transparent plate 1017holds the light entrance face 1021 a of the light condensing member 1021over a plane via the adhesive layer 1018. Forming the adhesive layer1018 with resin-based transparent adhesive makes it possible to give ita refractive index of, for example, about 1.5, that is, a refractiveindex close to that (for example, 1.52) of the light condensing member1021. This helps greatly reduce reflection-induced loss of laser lightat the light entrance face 1021 a as compared with in a case where, forexample, a layer of air (with a refractive index of 1) exists betweenthe transparent plate 1017 and the light condensing member 1021. Theadhesive layer 1018 may be provided only in a peripheral part (ano-passage region through which laser light does not pass) of the lightentrance face 1021 a of the light condensing member 1021. In that case,the adhesive layer 1018 does not need to have a function of transmittinglaser light. Moreover, in that case, the transparent plate 1017 holdsthe light condensing member 1021 along lines. The transparent plate 1017is an example of a “holding member” according to the invention.

The light condensing member 1021 can be fixed to (held on) thetransparent plate 1017 without the adhesive layer 1018. Specifically,the light condensing member 1021 and the transparent plate 1017 may befixed together by optical contact bonding or fusion. Optical contactbonding is a technology in which the surfaces of two optical members arepolished with high precision and brought into intimate contact with eachother so that the two optical members are joined together byintermolecular attraction.

The transparent plate 1017 and the light condensing member 1021 may beformed by integral molding. In other words, a part corresponding to thetransparent plate 1017 may be formed in the light condensing member1021. The part corresponding to the transparent plate 1017 may then befitted into the opening 1013 a of the casing 1013 so that the casing1013 may support the light condensing member 1021. In that case, thecasing 1013 holds the part corresponding to the side faces of thetransparent plate 1017 along lines. The casing 1013 then holds the lightcondensing member 1021 in a no-passage region through which laser lightdoes not pass. The part corresponding to the transparent plate 1017 maybe formed larger than the opening 1013 a of the casing 1013 so that thepart corresponding to a peripheral part of the light entrance face ofthe transparent plate 1017 may be bonded to the casing 1013. Also inthat case, the casing 1013 holds the light condensing member 1021 alonglines. Moreover, the casing 1013 holds the light condensing member 1021in the no-passage region through which laser light does not pass. In acase where a part corresponding to the transparent plate 1017 is formedin the light condensing member 1021, the casing 1013 serves as a“holding member” according to the invention.

As shown in FIG. 47, the light projecting unit 1020 includes a lightcondensing member 1021 which is disposed on the laser light exit side ofthe laser generating device 1010 (the semiconductor laser elements 11)and which guides the laser light from the laser generating device 1010while condensing it, a fluorescent member 1022 which converts at leastpart of the laser light emanating from the light condensing member 1021to emit fluorescence, a reflecting member 1023 which reflects thefluorescence emanating from the fluorescent member 1022 in apredetermined direction (direction A), a fitting member 1024 to whichthe fluorescent member 1022 is fixed, and a filter member 1025 which isdisposed at an opening of the reflecting member 1023. In thisembodiment, the light condensing member 1021, the fluorescent member1022, and the reflecting member 1023 of the light projecting unit 1020and the transparent plate 1017 and the adhesive layer 1018 of the lasergenerating device 1010 (or the casing 1013 of the laser generatingdevice 1010) constitute a light condensing unit 1030.

The light condensing member 1021 is formed as a member that transmitslight, and is formed of a substance that has a higher refractive indexthan the environment (air) around the light condensing member 1021.Examples of the material for the light condensing member 1021 includeglass, such as borosilicate crown glass (BK7) and artificial quartz, andresin. As shown in FIG. 53, the light condensing member 1021 includes alight entrance face 1021 a through which the laser light emanating fromthe semiconductor laser elements 11 enters; a light exit face 1021 bthrough which the laser light exits; and a top face 1021 c, a bottomface 1021 d, and a pair of side end faces 1021 e which are located(connect) between the light entrance face 1021 a and the light exit face1021 b. The top face 1021 c, the bottom face 1021 d, and the side endfaces 1021 e are an example of a “side face” according to the invention.

The light entrance face 1021 a is formed as, for example, asubstantially rectangular flat surface. The light exit face 1021 b isformed as, for example, a substantially square (rectangular) flatsurface, and has a smaller area than the light entrance face 1021 a.Specifically, as shown in FIGS. 54 and 55, the light entrance face 1021a has a height (H1021 a) of about 2.24 mm and a width (W1021 a) of about11.0 mm; the light exit face 1021 b has a height (H1021 b) of about 1.03mm and a width (W1021 b) of about 1.03 mm. Thus, the light condensingmember 1021 is formed in a shape that tapers off both in its width andthickness directions. The light entrance face 1021 a and the light exitface 1021 b may be coated with an unillustrated anti-reflection (AR)film.

The light exit face 1021 b may be formed as a coarse surface like thesurface of ground glass or a so-called moth-eye surface. This, asexperimentally verified, greatly improved the efficiency with whichlaser light is taken out of the light condensing member 1021 through thelight exit face 1021 b. In a case where the light exit face 1021 b is aflat surface, when the laser light reaches the light exit face 1021 binside the light condensing member 1021, part of it is reflected on theinner side of the light exit face 1021 b and thus cannot be taken out.By contrast, forming the light exit face 1021 b as a coarse surface likethe surface of ground glass or a so-called moth-eye surface helpssuppress reflection on the inner side of the light exit face 1021 b, andthus makes it possible to take out light efficiently.

The top face 1021 c and the bottom face 1021 d are formed in the sameshape, and the two side end faces 1021 e are formed in the same shape.The top face 1021 c, the bottom face 1021 d, and the side end faces 1021e all have a length (L1021) of about 50 mm. The angles (θ1021 c andθ1021 d) of the top face 1021 c and the bottom face 1021 d,respectively, with respect to the light entrance face 1021 a are largerthan the angle (θ1021 e) of the side end faces 1021 e with respect tothe light entrance face 1021 a.

The top face 1021 c, the bottom face 1021 d, and the side end faces 1021e have a function of reflecting the laser light that has entered throughthe light entrance face 1021 a to guide it to the light exit face 1021b.

Now, how the laser light that has entered the light condensing member1021 travels will be described briefly. As shown in FIGS. 56 and 57, thelaser light emanating from the semiconductor laser elements 11 travelswhile spreading in the major- and minor-axis directions, and enters thelight condensing member 1021 through the light entrance face 1021 a. Thelaser light is then subjected to repeated total reflection on the topface 1021 c, the bottom face 1021 d, and the side end faces 1021 e sothat it is, while being condensed, guided to the light exit face 1021 b;the laser light then exits through the light exit face 1021 b. Thus, thelight condensing member 1021 has a function of guiding the laser lightthat has entered through the light entrance face 1021 a to the lightexit face 1021 b while altering the travel direction of the laser lightinside the light condensing member 1021. The laser light emanating fromthe semiconductor laser elements 11 has a larger spread angle in themajor-axis direction than in the minor-axis direction, and thus thetotal reflection condition is more difficult to fulfill on the top face1021 c and the bottom face 1021 d. To cope with this, the angles (θ1021c and θ1021 d; see FIG. 55) of the top face 1021 c and the bottom face1021 d with respect to the light entrance face 1021 a is made largerthan the angle (θ1021 e; see FIG. 54) of the side end faces 1021 e withrespect to the light entrance face 1021 a, so that the total reflectioncondition is easier to fulfill on the top face 1021 c and the bottomface 1021 d.

As shown in FIG. 58, arranging the semiconductor laser elements 11 suchthat their respective laser light emission directions (the directions ofthe optical axes of the laser light they emit) point to about the centerof the light exit face 1021 b of the light condensing member 1021 isparticularly effective, because doing so makes the total reflectioncondition easier to fulfill on the side end faces 1021 e. In a casewhere the semiconductor laser elements 11 are arranged such that theirrespective laser light emission directions point to about the center ofthe light exit face 1021 b, as shown in FIG. 59, the light entrance face1021 a may be formed so as to be perpendicular to those laser lightemission directions. This helps suppress lowering in the efficiency withwhich laser light enters the light condensing member 1021.

As shown in FIGS. 60 to 62, the light condensing member 1021 may bechamfered at edges. Specifically, the light condensing member 1021 maybe given, on a plane perpendicular to its light guide direction, a crosssection in the shape of a rectangle chamfered at corners. In that case,as shown in FIGS. 60 and 61, the light condensing member 1021 may beflat-chamfered at edges (corners in the cross section) with a chamferwidth of 0.3 mm; instead, as shown in FIG. 62, the light condensingmember 21 may be round-chamfered at the edges so that the light exitface 1021 b may be formed in a substantially circular shape. The lightguide direction of the light condensing member 1021 denotes thedirection pointing from the center of the light entrance face 1021 a tothe center of the light exit face 1021 b. Giving the light condensingmember 1021, on a plane perpendicular to its light guide direction, arectangular shape chamfered at corners makes it possible to suppressscattering of laser light at edges (corners in the cross section) of thelight condensing member 1021. This helps suppress leakage of laser lightout of the light condensing member 1021, and thus helps improve theefficiency of use of laser light.

In this embodiment, the light intensity distribution of the laser lightat the light exit face 1021 b of the light condensing member 1021 iseven as shown in FIG. 63. That is, the light intensity distribution ofthe laser light emanating from the light exit face 1021 b is notGaussian. This helps prevent excessive light density in part of theirradiated face 1022 a, which will be described later, of thefluorescent member 1022. In this way, it is possible to preventheat-induced deterioration, and deterioration through a light-inducedchemical reaction, of the phosphor and binder contained in thefluorescent member 1022.

As shown in FIG. 64, the light condensing member 1021 is inclined indirection B (the direction opposite to the light projection direction(the predetermined direction, direction A)). Moreover, between the lightexit face 1021 b of the light condensing member 1021 and the irradiatedface 1022 a of the fluorescent member 1022, a gap (space) is formed.

The fluorescent member 1022 has an irradiated face 1022 a which isirradiated with laser light. The rear face (the face opposite from theirradiated face 1022 a) of the fluorescent member 1022 makes contactwith the support plate 1026, which is made of aluminum. As shown in FIG.65, a central part of the irradiated face 1022 a of the fluorescentmember 1022 is irradiated with the laser light condensed through thelight condensing member 1021. Here, the region irradiated with laserlight in the central part of the irradiated face 1022 a has a diameterof about 2 mm. The fluorescent member 1022 may be formed to have adiameter of about 2 mm so that laser light may be shone onto the entireirradiated face 1022 a of the irradiated face 1022 a.

The fluorescent member 1022 is formed by use of particles of three kindsof phosphors (fluorescent or phosphorescent substances) that convert,for example, blue-violet light (exciting light) into red, green, andblue light respectively and emit the results. An example of the phosphorthat converts blue-violet light into red light is CaAlSiN₃:Eu. Anexample of the phosphor that converts blue-violet light into green lightis β-SiAlON:Eu. An example of the phosphor that converts blue-violetlight into blue light is (Ba,Sr)MgAl₁₀O₁₇:Eu. These phosphors are boundtogether by an inorganic binder (such as silica or TiO₂). The red,green, and blue fluorescence emanating from the fluorescent member 1022mixes to produce white light. Here, red light is light with a centerwavelength of, for example, about 640 nm, green light is light with acenter wavelength of, for example, about 520 nm, and blue light is lightwith a center wavelength of, for example, about 450 nm.

As shown in FIG. 47, the fluorescent member 1022 is disposed in a regionon the reflecting member 1023 which includes the focus F1023 of thereflecting face 1023 a, and the center of the irradiated face 1022 a ofthe fluorescent member 1022 approximately coincides with the focus F1023of the reflecting face 1023 a. The fluorescent member 1022 may bedisposed near the focus F1023 of the reflecting face 1023 a on thereflecting member 1023. As shown in FIG. 64, the irradiated face 1022 aof the fluorescent member 1022 is inclined upward in the lightprojection direction (direction A).

As shown in FIG. 66, the reflecting face 1023 a of the reflecting member1023 is disposed so as to face the irradiated face 1022 a of thefluorescent member 1022. The reflecting face 1023 a is formed so as toinclude, for example, part of a paraboloid. Specifically, the reflectingface 1023 a is formed in the shape of a paraboloid that is split on theplane perpendicular to (crossing) the axis through its vertex V1023 andfocus F1023 and that is further split on the plane parallel to the axisthrough the vertex V1023 and focus F1023. As shown in FIGS. 66 and 67,the reflecting face 1023 a has a depth (length in direction B) of about30 mm, and is formed substantially in a semicircular shape with a radiusof about 30 mm as seen from the light projection direction (directionA).

The reflecting face 1023 a has a function of reflecting, while makinginto parallel light, the light from the fluorescent member 1022 in apredetermined direction (direction A). In practice, the laser light spotregion (the irradiated region) on the irradiated face 1022 a has acertain size, and thus the light emanating from the reflecting member1023 is not exactly parallel; in the present specification, however, forthe sake of simple description, the light emanating from the reflectingmember 1023 is occasionally referred to as being parallel.

In a part of the reflecting member 1023 deviated from the center of thefluorescent member 1022 in direction B, a through hole 1023 b is formed.In the through hole 1023 b, a tip-end part of the light condensingmember 1021 is inserted.

The reflecting member 1023 may be formed of metal, or may be formed bycoating the surface of resin with a reflective film.

To the reflecting member 1023, a fitting member 1024 is fixed.Preferably, the top face 1024 a of the fitting member 1024 is formed soas to having a function of reflecting light. The fitting member 1024 isformed of metal with good thermal conductivity, such as Al or Cu, so asto having a function of dissipating the heat generated in thefluorescent member 1022. On the top face 1024 a of the fitting member1024, a fitting portion 1024 b on which to fix the fluorescent member1022 and the support plate 1026 is formed integrally. As shown in FIG.64, the fitting face 1024 c of the fitting portion 1024 b is inclinedupward in the light projection direction (direction A). Preferably, onthe bottom face of the fitting member 1024, heat dissipating fins(unillustrated) are provided.

As shown in FIG. 47, the opening (the end in direction A) of thereflecting member 1023 is fitted with a filter member 1025 which shields(absorbs or reflects) exciting light (light with a wavelength of about405 nm) but transmits the fluorescence (red, green, and blue light)resulting from the wavelength conversion by the fluorescent member 1022.Specifically, the filter member 1025 may be formed of a glass materialsuch as, for example, ITY-418 manufactured by Isuzu Glass Co., Ltd.,which absorbs light with wavelengths of 418 nm or less and transmitslight with wavelengths more than 418 nm, or, for example, L42manufacture by Hoya Corporation, which absorbs light with wavelengths of420 nm or less and transmits light with wavelengths more than 420 nm.Providing the filter member 1025 at the opening of the reflecting member1023 helps reduce leakage of laser light.

In this embodiment, as described above, the light condensing member 1021is provided which includes the light entrance face 1021 a through whichlaser light enters and the light exit face 1021 b which has a smallerarea than the light entrance face 1021 a and through which the laserlight exits, and the light condensing member 1021 includes the sidefaces (the top face 1021 c, the bottom face 1021 d, and the side endfaces 1021 e) which reflect the laser light that has entered through thelight entrance face 1021 a to guide it to the light exit face 1021 b.Thus, the laser light that has entered through the light entrance face1021 a is, while being reflected on the side faces, guided to the lightexit face 1021 b, and then exits through the light exit face 1021 b in acondensed state. This helps increase the density of the laser lightemanating from the light condensing member 1021. Moreover, the laserlight that has entered through the light entrance face 1021 a travelsinside the light condensing member 1021 while being totally reflected onthe side faces and exits through the light exit face 1021 b with an evenlight intensity distribution. That is, the light intensity distributionof the laser light emanating from the light exit face 1021 b is notGaussian. This helps prevent excessively high light density in part ofthe irradiated face of the fluorescent member 1022. Thus, it is possibleto prevent heat-induced deterioration, and deterioration through alight-induced chemical reaction, of the phosphor and binder contained inthe fluorescent member 1022.

Moreover, as described above, the transparent plate 1017 which holds thelight condensing member 1021 holds the light entrance face 1021 a. Thus,when laser light is reflected on the side faces, it is not absorbed bythe transparent plate 1017. This helps suppress lowering in theefficiency of use of laser light.

Moreover, as described above, the transparent plate 1017 has a functionof transmitting laser light. This helps suppress absorption of laserlight by the transparent plate 1017, and permits the transparent plate1017 to be disposed so as to cover the light entrance face 1021 a. Thus,the light entrance face 1021 a can easily be held by the transparentplate 1017.

Moreover, as described above, a part corresponding to the transparentplate 1017 may be integrally formed with the light condensing member1021 so that the light condensing member 1021 may be held by the casing1013.

Moreover, as described above, by use of the light condensing member 1021into which the laser light emanating from the semiconductor laserelements 11 is shone, the laser light emanating from the semiconductorlaser elements 11 can easily be condensed. Thus, using the lightcondensing member 1021 is particularly effective in cases where aplurality of semiconductor laser elements 11 are used as a laser lightsource.

Moreover, as described above, forming the light exit face 1021 b as acoarse surface or a moth-eye surface helps reduce reflection on theinner side of the light exit face 1021 b, and thus makes it possible totake out light efficiently.

Moreover, as described above, in a case where a part corresponding tothe transparent plate 1017 is formed integrally with the lightcondensing member 1021, the casing 1013 holds the light condensingmember 1021 in a no-passage region through which laser light does notpass. This prevents laser light from being absorbed by the casing 1013,and thus helps suppress lowering in the efficiency of use of light.

Ninth Embodiment

As a ninth embodiment, with reference to FIGS. 68 to 72, a descriptionwill be given of a case where, unlike in the eighth embodiment describedpreviously, a holding member 1110 holds a side face of the lightcondensing member 1021.

As shown in FIG. 68, the light condensing unit according to the ninthembodiment of the invention includes a light condensing member 1021 anda holding member 1110 which holds the light condensing member 1021. InFIG. 68, hatching indicates metal belts 1111, which will be describedlater, of the holding member 1110. The light condensing member 1021 isdisposed at a predetermined distance (gap) from the transparent plate1017 of the laser generating device 1010, and the holding member 1110 isprovided as a separate member from the laser generating device 1010.

As shown in FIGS. 69 and 70, in the light condensing member 1021 in thisembodiment, the light entrance face 1021 a has a height (H1021 a) ofabout 6.0 mm and a width (W1021 a) of about 23.4 mm. The light entranceface 1021 a divides into three parts 1121 a, 1121 b, and 1121 c. Thepart 1121 a has a width (W1121 a) of about 11.44 mm. The parts 1121 band 1121 c are inclined by about 5.46 degrees toward the light exit face1021 b with respect to the part 1121 a.

The light exit face 1021 b has a height (H1021 b) of about 2.66 mm and awidth (W1021 b) of about 2.66 mm. The side end faces 1021 e are inclinedby about 4.96 degrees in the light guide direction. The top face 1021 cand the bottom face 1021 d have a length (L1021) of about 120 mm.

In this embodiment, as shown in FIG. 71, as a laser light source, threesemiconductor laser elements 11 are provided. The semiconductor laserelements 11 are disposed one for each of the three parts 1121 a to 1121c of the light entrance face 1021 a. Moreover, the semiconductor laserelements 11 are disposed so that the directions in which theyrespectively emit light point to about the center of the light exit face1021 b of the light condensing member 1021. On the light entrance face1021 a, the distance (L1021 a) from the center axes of the semiconductorlaser elements 11 disposed at both ends to the respective side end faces1021 e is about 0.3 mm.

As shown in FIG. 68, the holding member 1110 includes a plurality ofmetal belts 1111 (line contact portions) that make line contact with thelight condensing member 1021. These metal belts 1111 are made of metal,and has a function of reflecting light. The metal belts 1111 areprovided on a light entrance face 1021 a side end part and a light exitface 1021 b end part of the side faces (the top face 1021 c, the bottomface 1021 d, and the side end faces 1021 e). Each belt 1111 is formedwith a width (W1111; see FIG. 71) of, for example, 5 mm or less. Themetal belts 1111 may be formed by bending a metal plate, or may bedeposited as a thin film on the surface of the light condensing member1021.

The holding member 1110 includes a member like a body portion 1212 inthe tenth embodiment described later, and this member couples to themetal belts 1111. The holding member 1110 holds the side faces of thelight condensing member 1021 along lines.

In other respects, the structure of the ninth embodiment is similar tothat of the eighth embodiment described previously.

In this embodiment, as described above, the holding member 1110 holdsthe side faces (the top face 1021 c, the bottom face 1021 d, and theside end faces 1021 e) of the light condensing member 1021 along lines.This helps sufficiently reduce the contact area between the lightcondensing member 1021 and the holding member 1110. This helps suppressabsorption of laser light by the holding member 1110 as a result oflaser light exiting into the holding member 1110 due to the totalreflection condition failing to be fulfilled at where the lightcondensing member 1021 and the holding member 1110 make contact witheach other. That is, it is possible to reduce the amount of laser lightabsorbed by the holding member 1110. This helps suppress lowering in theefficiency of use of laser light.

Moreover, as described above, the holding member 1110 holds a lightentrance face 1021 a side part and a light exit face 1021 b part of theside faces (the top face 1021 c, the bottom face 1021 d, and the sideend faces 1021 e). This makes it possible to stably hold the lightcondensing member 1021.

Moreover, as described above, the holding member 1110 includes the metalbelts 1111 which make line contact with the light condensing member1021. This helps further reduce the amount of laser light absorbed bythe holding member 1110.

In other respects, the benefits of the ninth embodiment are similar tothose of the eighth embodiment described previously.

Next, with reference to FIG. 72, a description will be given ofexperiments conducted to verify the effects described above.

In the experiments, the output (amount of light) of the laser light onthe light exit face 1021 b of the light condensing member 1021 wasdetermined through simulation with the following examples: Example 1, inwhich the light entrance face 1021 a of the light condensing member 1021was held (corresponding to the eighth embodiment), and Examples 2-1 to2-3, which corresponded to the ninth embodiment.

In Example 1, the light condensing member 1021 and the transparent plate1017 were fixed together by optical contact bonding. In other respects,the structure was similar to that of the ninth embodiment describedabove. That is, Example 1 corresponded to the ninth embodiment with allthe metal belts 1111 given a width (W1111) of 0 mm.

In Example 2-1, the metal belts 1111 were given a width (W1111) of about1.6 mm. In Example 2-2, the metal belts 1111 were given a width (W1111)of about 3.1 mm. In Example 2-3, the metal belts 1111 were given a width(W1111) of about 5.1 mm. In other respects, the structure was similar tothat of the ninth embodiment described above.

With each of Examples 1 and 2-1 to 2-3, the amount of light of the laserlight on the light exit face 1021 b of the light condensing member 1021was determined and was normalized assuming that the value obtained withExample 1 was “1.” The results are shown in FIG. 72.

FIG. 72 reveals the following. Increasing the width of the metal belts1111 resulted in lowering the amount of light of the laser light on thelight exit face 1021 b. It was thus found that the metal belts 1111 thatmade contact with the side faces of the light condensing member 1021caused loss of light, and thus that, by reducing the contact areabetween the light condensing member 1021 and the holding member 1110(the width of the metal belts 1111), it was possible to suppresslowering in the efficiency of use of laser light. It was also foundthat, in a case where metal belts 1111 were used, they should better begiven a small width, and that, by giving the metal belts 1111 a width ofabout 1 mm or less, it was possible to reduce the loss of light to about5% or less. Specifically, the amount of light in Example 2-1 was about0.94, indicating a loss of about 6% in the amount of light; the amountof light in Example 2-2 was about 0.89, indicating a loss of about 11%in the amount of light; the amount of light in Example 2-3 was about0.83, indicating a loss of about 17% in the amount of light.

Tenth Embodiment

As a tenth embodiment, with reference to FIGS. 73 to 77, a descriptionwill given of a case where, unlike in the ninth embodiment describedpreviously, a holding member 1210 holds a side face of the lightcondensing member 1021 at points.

As shown in FIGS. 73 and 74, a light condensing unit according to thetenth embodiment of the invention includes a light condensing member1021 and a holding member 1210 (see FIG. 74) which holds the lightcondensing member 1021. In FIG. 73, for the sake of easy understanding,a body portion 1212 and restricting portions 1213, which will bedescribed later, of the holding member 1210 are omitted.

The holding member 1210 includes a plurality of posts 1211 (pointcontact portions) which make point contact with the light condensingmember 1021, a body portion 1212 (see FIG. 74) to which the posts 1211are fitted, and restricting portions 1213 (see FIG. 77), which will bedescribed later. The posts 1211 are provided in a light entrance face1021 a side end part and a light exit face 1021 b side end part of theside faces (the top face 1021 c, the 1021 d, and the side end faces 1021e) of the light condensing member 1021. For example, in the lightentrance face 1021 a side end part, posts 1211 are provided one on eachof the top face 1021 c, the bottom face 1021 d, and the side end faces1021 e; in the light exit face 1021 b side end part, posts 1211 areprovided one on each of the top face 1021 c, the bottom face 1021 d, andthe side end faces 1021 e.

Each post 1211 is formed substantially in a cylindrical shape, and itspart at which it makes contact with the light condensing member 1021 isformed in a hemispherical shape (with a curved surface). Thus, the posts1211 make point contact with the light condensing member 1021, and thusthe holding member 1210 holds the light condensing member 1021 atpoints. The posts 1211 have lower hardness than the light condensingmember 1021, and are formed of, for example, resin. The part of theposts 1211 at which they make contact with the light condensing member1021 does not necessarily have to be hemispherical but may be flat. Inthat case, the posts 1211 should better be fine.

As shown in FIG. 74, the posts 1211 are fitted in a plurality ofinsertion holes (unillustrated) provided in the body portion 1212. Theamount of protrusion of the posts 1211 may be made adjustable by formingscrew threads on them.

Here, as shown in FIG. 75, the light condensing member 1021 includes apassage region S1001 through which laser light passes and a no-passageregion S1002 (hatched in FIG. 75) through which laser light does notpass. In FIG. 73, in the light entrance face 1021 a side end part, posts1211 a are disposed on the passage region S1001, and posts 1211 b aredisposed on the no-passage region S1002. Instead, as shown in FIG. 76,the posts 1211 a too may be disposed on the no-passage region S1002. Inthat case, no laser light is absorbed by the holding member 1210, andthis helps further suppress lowering in the efficiency of use of laserlight. This design is particularly effective in cases where the part ofthe posts 1211 at which they make contact with the light condensingmember 1021 is flat.

As shown in FIGS. 74 and 77, the body portion 1212 is formed in atubular shape such as to cover the side faces of the light condensingmember 1021. Inside the body portion 1212, the light condensing member1021 and the posts 1211 are disposed.

As shown in FIG. 77, at the rear end of the body portion 1212,restricting portions 1213 are provided which prevent the lightcondensing member 1021 from moving rearward (direction E). Since thelight condensing member 1021 is formed in a shape that tapers off towardthe tip end, the light condensing member 1021 does not move frontward(direction F).

In other respects, the structure of the tenth embodiment is similar tothat of the ninth embodiment described previously.

In this embodiment, as described above, the holding member 1210 includesposts 1211 that make point contact with the light condensing member1021, and the posts 1211 have lower hardness than the light condensingmember 1021. This helps suppress damage inflicted on the lightcondensing member 1021 by the posts 1211 on the holding member 1210.

Moreover, as described above, forming the part of the posts 1211 atwhich they make contact with the light condensing member 1021 in ahemispherical shape (with a curved surface) helps make the contact areabetween the holding member 1210 and the light condensing member 1021extremely small, and thus helps further suppress lowering of theefficiency of use of laser light.

Moreover, as described above, the holding member 1210 is formed so as tocover the side faces (the top face 1021 c, the bottom face 1021 d, andthe light projection apparatus side end faces 1021 e). This helpssuppress leakage of the laser light exiting through the side faces ofthe light condensing member 1021 out of the light condensing unit 1030,and thus helps suppress adverse effects of laser light on the human eyeetc.

In other respects, the benefits of the tenth embodiment are similar tothose of the eighth and ninth embodiments described previously.

Eleventh Embodiment

As an eleventh embodiment, with reference to FIGS. 78 and 79, adescription will be given of a case where, unlike in the ninth and tenthembodiments described previously, metal wires 1311 of a holding member1310 hold the side faces of the light condensing member 1021.

As shown in FIGS. 78 and 79, a light condensing unit according to theeleventh embodiment of the invention includes a light condensing member1021 and a holding member 1310 which holds the light condensing member1021. The holding member 1310 includes a plurality of metal wires 1311(line contact portions) which make line contact with the lightcondensing member 1021. In FIGS. 78 and 79, for the sake of easyunderstanding, the part of the holding member 1310 other than the metalwires 1311 is omitted. As shown in FIG. 79, the metal wires 1311 areeach bent so as to make contact with two contiguous ones of the sidefaces of the light condensing member 1021.

The holding member 1310 includes, though not shown, a member like thebody portion 1212 in the tenth embodiment described previously, and thismember couples to the metal wires 1311. The holding member 1310 holdsthe side faces of the light condensing member 1021 along lines.

In other respects, the structure and benefits of the eleventh embodimentare similar to those of the ninth and tenth embodiments describedpreviously.

Twelfth Embodiment

As a twelfth embodiment, with reference to FIG. 80, a description willbe given of a case where, unlike in the ninth to eleventh embodimentsdescribed previously, a holding member 1410 makes contact only with thevertices of the cross section of the light condensing member 1021.

As shown in FIG. 80, a light condensing unit according to the twelfthembodiment of the invention includes a light condensing member 1021 anda holding member 1410 which holds the light condensing member 1021. Theholding member 1410 is formed so as to have a C-shaped cross section inthe shape of an ellipse having a part thereof cut out. Thus, spreadingthe holding member 1410 and inserting the light condensing member 1021into it results in the inner surface of the holding member 1410 makingcontact with the vertices (in the diagram, four vertices) of the lightcondensing member 1021 in its section perpendicular to the light guidedirection. Here, the holding member 1410 holds the light condensingmember 1021 along lines.

The holding member 1410 covers the side faces of the light condensingmember 1021. Moreover, the holding member 1410 is formed so as to havelower hardness than the light condensing member 1021, and is formed of,for example, resin.

In other respects, the structure of the twelfth embodiment is similar tothat of the ninth to eleventh embodiments described previously.

In this embodiment, as described above, the holding member 1410 makescontact with a plurality of vertices in the cross section of the lightcondensing member 1021 perpendicular to the light guide direction. Thus,the holding member 1410 can be brought into line contact with the lightcondensing member 1021, and this helps reduce the amount of laser lightabsorbed by the holding member 1410. Moreover, the laser light guidedinside the light condensing member 1021 is less likely to reach thevertices of the cross section of the light condensing member 1021. Thatis, the density of laser light at the vertices of the light condensingmember 1021 is lower than the density of laser light elsewhere. Thishelps further reduce the amount of laser light absorbed by the holdingmember 1410.

In other respects, the benefits of the twelfth embodiment are similar tothose of the eighth to eleventh embodiments described previously.

It should be understood that the eighth to twelfth embodiments presentedabove are in every respect only illustrative and not restrictive. Thescope of the present invention is defined not by the description of theeighth to twelfth embodiments presented above but by the appendedclaims, and encompasses all variations and modifications made within thespirit and scope equivalent to the claims.

For example, although the eighth to twelfth embodiments presented abovedeal with examples where a light emitting apparatus according to theinvention is used as a headlamp of an automobile, this is not meant tobe any limitation. A light emitting apparatus according to the inventionmay be used as a headlamp of an airplane, ship, robot, motorcycle,bicycle, or any other mobile body.

Although the eighth to twelfth embodiments presented above deal withexamples where a light emitting apparatus according to the invention isapplied to a headlamp, this is not meant to be any limitation. A lightemitting apparatus according to the invention may be applied to adownlight, spotlight, or any other type of light projection apparatus.

Although the eighth to twelfth embodiments presented above deal withexamples where the exciting light is converted into visible light, thisis not meant to be any limitation; the exciting light may instead beconverted into any light other than visible light. For example, a designthat converts the exciting light into infrared light finds applicationin, for example, night vision illumination apparatus for surveillanceCCD cameras.

Although the eighth to twelfth embodiments presented above deal withexamples where the exciting light source (semiconductor laser element)and the fluorescent member are designed to emit white light, this is notmeant to be any limitation. The exciting light source and thefluorescent member may be designed to emit light other than white light.

Although the eighth to twelfth embodiments presented above deal withexamples where the fluorescent member is disposed near the tip end ofthe light condensing member and is excited to obtain a point lightsource, this is not meant to be any limitation; the fluorescent memberdoes not necessarily have to be disposed near the tip end of the lightcondensing member. In that case, for example, the light emittingapparatus may be used as a light source for melting a soldering materialplaced near the tip end of the light condensing member. Light of awavelength of 405 nm is suitable for melting Au, and thus allows easylaser welding. For another example, the light emitting apparatus may beused as an exposing light source for exposing a photosensitive materialplaced near the tip end of the light condensing member. This helpsgreatly shorten the exposure time of the photosensitive material. Foryet another example, the light emitting apparatus may be used as a lightsource in an ultraviolet microscope for inspection of the shapes ofobjects under ultraviolet light.

Although the eighth to twelfth embodiments presented above deal withexamples where a semiconductor laser element is used as a lasergenerator for emitting laser light, this is not meant to be anylimitation; any laser generator other than a semiconductor laser elementmay instead be used.

All specific values mentioned above in connection with the eighth totwelfth embodiments presented above are merely examples, and are notmeant to be any limitation.

In the eighth to twelfth embodiments presented above, the centerwavelength of the laser light emitted by the semiconductor laserelement, and the kind of phosphor used in the fluorescent member, may bechanged as desired. For example, in cases where laser light can be usedsafely as illumination light, it is possible to use a semiconductorlaser element that emits blue laser light with a center wavelength ofabout 450 nm in combination with a phosphor that converts part of theblue laser light into yellow light in order to obtain white light. Inthat case, no filter member for shielding the exciting light needs to beprovided. One example of the phosphor that converts part of blue laserlight into yellow light is (Y_(1-x-y)Gd_(x)Ce_(y))₃Al₅O₁₂ (0.1≦x≦0.55,0.01≦y≦0.4). This is not meant to be any limitation; the centerwavelength of the laser light emitted by the semiconductor laser elementmay be selected as desired within the spectrum ranging from ultravioletto visible light.

Although the eighth to twelfth embodiments presented above deal withexamples where the light emanating from the irradiated face of thefluorescent member is used as illumination light, this is not meant tobe any limitation; the light emanating from the rear face (the faceopposite from the irradiated face) or a side face of the fluorescentmember may be used as illumination light.

Although the eighth to twelfth embodiments presented above deal withexamples where the reflecting face of the reflecting member is formed aspart of a paraboloid, this is not meant to be any limitation; thereflecting face may instead be formed as part of an ellipsoid. In thatcase, disposing the fluorescent member at the focus of the reflectingface makes it easy to condense the light emitted from the light emittingapparatus. The reflecting face may even be formed as a multiplereflector composed of a number of curved surfaces (such as paraboloids),or as a free-form curved-surface reflector composed of a number ofminuscule flat surfaces provided contiguously.

Although the eighth to twelfth embodiments presented above deal withexamples where a plurality of semiconductor laser elements are used asan exciting light source, this is not meant to be any limitation. Asingle semiconductor laser element may instead be used as an excitinglight source. Or a so-called semiconductor laser array provided with aplurality of light emitting portions may be used as an exciting lightsource.

Although, for example, the ninth embodiment presented above deals withan example where metal belts are provided in a light entrance face sideend part and a light exit face side end part of a light condensingmember, this is not meant to be any limitation. For example, as in aholding member 1110 according to a sixth modified example of theinvention shown in FIG. 81, it is possible to provide metal belts 1111,on the light entrance face 1021 a side, in an end part of the lightcondensing member 1021 and, on the light exit face 1021 b side, awayfrom the end part (the light exit face 1021 b). In FIG. 81, hatchingindicates the metal belts 1111. The closer to the light exit face 1021b, the higher the density of laser light inside the light condensingmember 1021. Thus, disposing a metal belt 1111 away from the light exitface 1021 b permits the metal belt 1111 to hold a part where the lightdensity is lower. This helps reduce loss of laser light. The sameapplies equally to the tenth to twelfth embodiments presented above.

For another example, a metal belt 1111 may be provided only in a lightentrance face 1021 a side part, or only in a light exit face 1021 b sidepart, of the light condensing member 1021. The light condensing member1021 is bulkier and heavier in its light entrance face 1021 a side partthan in its light exit face 1021 b side part; therefore, holding thelight entrance face 1021 a side part allows more stable holding of thelight condensing member 1021. Moreover, less laser light reaches theside faces in the light entrance face 1021 a side part of the lightcondensing member 1021 than in its light exit face 1021 b side part.Thus, holding the light entrance face 1021 a side part helps furtherreduce the amount of laser light absorbed by the metal belts 1111.

Although the eighth to twelfth embodiments presented above deal withexamples where semiconductor laser elements 11 are arranged in a row,this is not meant to be any limitation; for example, a light emittingapparatus may be designed like one according to a seventh modifiedexample of the invention shown in FIG. 82. Specifically, semiconductorlaser elements 11 (see FIG. 83) in miniature packages 1511 may bearranged in a closest-packed fashion in two or three tiers (in FIG. 82,three tiers).

The shape of the light condensing member is not limited to those in theeighth to twelfth embodiments presented above, but may instead be as ina light condensing member 1021 in an eighth modified example of theinvention as shown in FIGS. 84 to 86. Specifically, in a case where thelight condensing member 1021 is formed of BK7, the relevant dimensionsmay be as follows: the height (H1021 a) of the light entrance face 1021a, about 3 mm; the width (W1021 a) of the light entrance face 1021 a,about 10 mm; the height (H1021 b) of the light exit face 1021 b, about 2mm; the width (W1021 b) of the light exit face 1021 b, about 2 mm; thelength (L1021) of the top face 1021 c, the bottom face 1021 d, and theside end faces 1021 e, about 50 mm; the angle (θ1021 c and θ1021 d) ofthe top face 1021 c and the bottom face 1021 d with respect to the lightentrance face 1021 a, about 88.9 degrees; the angle (θ1021 e) of theside end faces 1021 e with respect to the light entrance face 1021 a,about 80.9 degrees. In a case where the light condensing member 1021 isformed of artificial quart, the relevant dimensions may be as follows:the height (H1021 a) of the light entrance face 1021 a, about 6 mm; thewidth (W1021 a) of the light entrance face 1021 a, about 24 mm; theheight (H1021 b) of the light exit face 1021 b, about 3 mm; the width(W1021 b) of the light exit face 1021 b, about 3 mm; the length (L1021)of the top face 1021 c, the bottom face 1021 d, and the side end faces1021 e, about 120 mm; the angle (θ1021 c and θ1021 d) of the top face1021 c and the bottom face 1021 d with respect to the light entranceface 1021 a, about 88.6 degrees; the angle (θ1021 e) of the side endfaces 1021 e with respect to the light entrance face 1021 a, about 80.1degrees. Depending on the material used, the refractive index of thelight condensing member 1021 varies, and accordingly the shape(dimensions) of the light condensing member 1021 that efficiently guideslight vary.

In a case where the light condensing member is chamfered at edges, forexample as in a light condensing unit according to a ninth modifiedexample of the invention shown in FIG. 87, the chamfered faces of thelight condensing member 1021 may be held by a holding member 1610.Specifically, when the light condensing member 1021 is chamfered at thefour corners, its cross section perpendicular to the light guidedirection has an octagonal (polygonal) shape with eight sides and isline-symmetric both in the up-down and left-right directions. Here, thefour sides (chamfered faces) 1621 at the corners are the shortest sides.These four sides 1621 are inclined, for example, at 45 degrees withrespect to the side faces. The holding member 1610 holds the lightcondensing member 1021 by making contact with at least one of the foursides 1621. For stable holding of the light condensing member 1021, itis preferable that the holding member 1610 hold two or more of the sides1621, and more preferably all the four sides 1621. Holding the chamferedfaces of the light condensing member 1021 with the holding member 1610in this way makes it easy to hold the light condensing member 1021stably. The holding member 1610 may hold the light condensing member1021 along lines in the directions in which the sides 1621 extend (thedirection approximately perpendicular to the plane of paper), or may bearranged at predetermined intervals in the direction in which the sides1621 extend and hold the light condensing member 1021 at points.Needless to say, by use of the holding member 1410 of the twelfthembodiment presented above, the light condensing member 1021 in FIG. 87may be held at a plurality of vertices.

Although, for example, the tenth embodiment presented above deals withan example where the body portion 1212 of the holding member 1210 isprovided so as to cover the light condensing member 1021 up to a tip-endpart thereof (a part thereof near the light exit face 1021 b), this isnot meant to be any limitation. For example, as in a light emittingapparatus according to a tenth modified example of the invention shownin FIG. 88, the tip-end part of the light condensing member 1021 mayprotrude from a body portion 1712 of a holding member 1710. With thisdesign, when the holding member 1710 is incorporated in the lightemitting apparatus 1001 of the eighth embodiment presented above, theholding member 1710 can be disposed outside the reflecting member 1023.This helps prevent the light emanating from the fluorescent member 1022from being shielded by the holding member 1710, and thus helps furtherreduce loss of light. The holding member 1710 may be fixed to thereflecting member 1023 or the fitting member 1024. The same is true withthe ninth, eleventh, and twelfth embodiments presented above.

The invention encompasses in its technical scope any designs obtained byappropriately combining together features from different ones of theembodiments and modified examples presented above.

What is claimed is:
 1. A light projection apparatus, comprising: afluorescent member which is excited with exciting light; and a lightprojecting member which reflects or transmits light emanating from thefluorescent member to project the light outside, wherein the fluorescentmember includes an irradiated face, and the irradiated face includes anirradiated region which is irradiated with the exciting light such thata length of the irradiated region in a first direction is greater than alength of the irradiated region in a second direction perpendicular tothe first direction and parallel to the irradiated face of thefluorescent member.
 2. The light projection apparatus according to claim1, further comprising a light condensing member which includes a lightentrance face through which the exciting light enters and a light exitface that has a smaller area than the light entrance face and throughwhich the exciting light exits, wherein a length of the light exit facein the first direction is greater than a length of the light exit facein the second direction.
 3. The light projection apparatus according toclaim 1, wherein the irradiated region has a rectangular, elliptical, orelongate hexagonal shape.
 4. The light projection apparatus according toclaim 1, wherein the light projecting member includes a reflectingmember which reflects the light emanating from the fluorescent member toproject the light outside.
 5. The light projection apparatus accordingto claim 1, wherein the exciting light includes laser light.